Active control of light emitting diodes and light emitting diode displays

ABSTRACT

Active control of light emitting diodes (LEDs) and LED packages within LED displays is disclosed. LED packages are disclosed that include a plurality of LED chips that form at least one LED pixel for an LED display or an LED panel. Each LED package may include an active electrical element that is configured to receive a control signal and actively maintain an operating state, such as brightness or grey level while other LED packages are being addressed. Active electrical elements are disclosed that are configured to provide both forward and reverse bias states to LEDs to detect adverse operating conditions including reverse leakage and deviations to forward voltage levels. LED packages are also disclosed that may self-configure based on the manner in which various input or output lines are connected.

RELATED APPLICATIONS

This application is continuation-in-part of U.S. patent application Ser.No. 16/437,878, filed Jun. 11, 2019, which is a continuation-in-part ofU.S. patent application Ser. No. 16/369,003, filed Mar. 29, 2019, thedisclosures of which are hereby incorporated herein by reference intheir entireties.

FIELD OF THE DISCLOSURE

The present disclosure relates to solid-state lighting devices includinglight-emitting diode devices and light-emitting diode displays.

BACKGROUND

Light emitting diodes (LEDs) are solid-state devices that convertelectrical energy to light and generally include one or more activelayers of semiconductor material (or an active region) arranged betweenoppositely doped n-type and p-type layers. When a bias is applied acrossthe doped layers, holes and electrons are injected into the one or moreactive layers where they recombine to generate emissions such as visiblelight or ultraviolet emissions. An LED chip typically includes an activeregion that may be fabricated, for example, from epitaxial layers ofsilicon carbide, gallium nitride, aluminum gallium nitride, indiumnitride, gallium phosphide, aluminum nitride, gallium arsenide-basedmaterials, and/or from organic semiconductor materials.

LEDs have been widely adopted in various illumination contexts, forbacklighting of liquid crystal display (LCD) systems (e.g., as asubstitute for cold cathode fluorescent lamps), and for direct-view LEDdisplays. Applications utilizing LED arrays include vehicular headlamps,roadway illumination, light fixtures, and various indoor, outdoor, andspecialty contexts. Desirable characteristics of LED devices includehigh luminous efficacy, long lifetime, and wide color gamut.

Conventional LCD systems require polarizers and color filters (e.g.,red, green, and blue) that inherently reduce light utilizationefficiency. Direct-view LED displays, which utilize self-emitting LEDsand dispense with the need for backlights, polarizers, and colorfilters, provide enhanced light utilization efficiency.

Large format multi-color direct-view LED displays (including full colorLED video screens) typically include numerous individual LED panels,packages, and/or components providing image resolution determined by thedistance between adjacent pixels or “pixel pitch.” Direct-view LEDdisplays include three-color displays with arrayed red, green, and blue(RGB) LEDs, and two-color displays with arrayed red and green (RG) LEDs.Other colors and combinations of colors may be used. Large formatdisplays (e.g., electronic billboards and stadium displays) intended forviewing from great distances typically have relatively large pixelpitches and usually include discrete LED arrays with multi-color (e.g.,red, green, and blue) LEDs that may be independently operated to formwhat appears to a viewer to be a full-color pixel. Medium-sized displayswith relatively smaller viewing distances require shorter pixel pitches(e.g., 3 mm or less), and may include panels with arrayed red, green,and blue LED components mounted on a single electronic device attachedto a driver printed circuit board that controls the LEDs. Driver printedcircuit boards are typically densely populated with electrical devicesincluding capacitors, field effect transistors (FETs), decoders,microcontrollers, and the like for driving the pixels of the display. Aspixel pitches continue to decrease for higher resolution displays, thedensity of such electrical devices scales higher corresponding to theincreased number of pixels for a given panel area. This tends to addhigher complexity and costs to LED panels for display applications aswell as increase thermal crowding in areas where driver electronics aremore closely spaced.

The art continues to seek improved LED array devices with small pixelpitches while overcoming limitations associated with conventionaldevices and production methods.

SUMMARY

The present disclosure relates to light emitting diodes (LEDs), LEDpackages, and related LED displays, and more particularly to activecontrol of LEDs within LED displays. LED displays may include rows andcolumns of LED diodes that form an array of LED pixels. A particular LEDpixel may include a cluster of LED chips of the same color or multiplecolors, with an exemplary LED pixel including a red LED chip, a greenLED chip, and a blue LED chip. In certain embodiments, an LED packageincludes a plurality of LED chips that form at least one LED pixel and aplurality of such LED packages may be arranged to form an array of LEDpixels for an LED display. Each LED package may include an activeelectrical element that is configured to receive a control signal andactively maintain an operating state, such as brightness or grey level,or a color select signal for the LED chips of the LED package whileother LED packages are being addressed. In certain embodiments, theactive electrical element may include active circuitry that includes oneor more of a driver device, a signal conditioning or transformationdevice, a memory device, a decoder device, an electrostatic discharge(ESD) protection device, a thermal management device, and a detectiondevice, among others. In this regard, each LED pixel of an LED displaymay be configured for operation with active matrix addressing. Theactive electrical element may be configured to receive one or more of ananalog control signal, an encoded analog control signal, a digitalcontrol signal, and an encoded digital control signal. Display panelsare disclosed that include an array of such LED pixels on a first faceof a panel and control circuitry on a backside of the panel that isconfigured to communicate with each active electrical element of the LEDpixels.

Data signals sent to active electrical elements may include compresseddata codes that are subsequently decompressed, and one or more oftransfer functions, gamma correction, and color depth data. Activeelectrical elements are disclosed that are configured to provide bothforward and reverse bias states to LEDs in order to detect adverseoperating conditions such as reverse leakage and deviations to forwardvoltage levels. Such adverse operating conditions may be performed aspart of a self-check routine for an LED package. Active electricalelements as disclosed herein may comprise analog-to-digital converters(ADCs). LED packages are also disclosed that may self-configure based onthe manner in which various input or output lines are connected.

In one aspect, an LED package comprises: at least one LED; and an activeelectrical element electrically connected to the at least one LED, theactive electrical element configured to receive data values andtransform the data values according to a transfer function. In certainembodiments, the transfer function is a linear function. In certainembodiments, the transfer function is a nonlinear function. In certainembodiments, the transfer function comprises one or more subsets oftransfer function coefficients for the active electrical element tointerpolate. In certain embodiments, the transfer function comprises apiecewise transfer function. In certain embodiments, the data valuescomprise a compressed data code that is received by the activeelectrical element, and the active electrical element is configured totransform the compressed data code to a decompressed data code. Incertain embodiments, the decompressed data code comprises a brightnesslevel for the at least one LED. In certain embodiments, the decompresseddata code comprises a higher dynamic range than the compressed datacode. In certain embodiments, transformation of the compressed data codeto the decompressed data code follows a power law expression for gammacorrection. In certain embodiments, the at least one LED comprises twoor more adjacent LED pixels and the decompressed data code is determinedbased on a redundancy of data expected between neighboring ones of thetwo or more adjacent LED pixels. In certain embodiments, the data valuesare received from multiple sources. In certain embodiments, the activeelectrical element is configured to receive at least one of parametersand options of the transfer function at any of the plurality ofconnection ports. In certain embodiments, the plurality of connectionports comprise a plurality of polarity-agnostic connection ports. Incertain embodiments, the transfer function is applied to direct atemperature measurement of the at least one LED. In certain embodiments,the transfer function is applied to direct a brightness output of the atleast one LED. In certain embodiments, the active electrical elementcomprises an analog-to-digital converter and the transfer function isapplied to an output of the analog-to-digital converter. In certainembodiments, the active electrical element comprises a pulse widthmodulation controller and the transfer function is applied to direct anoutput of the pulse width modulation controller. In certain embodiments,the active electrical element comprises a digital-to-analog converterand the transfer function is applied to direct an output of thedigital-to-analog converter. In certain embodiments, the activeelectrical element is configured to drive the at least one LED andswitch between a forward bias state and a reverse bias state for the atleast one LED. In certain embodiments, the active electrical element isconfigured to receive selectable color depth data. In certainembodiments, the active electrical element comprises at least twobidirectional communication ports. In certain embodiments, the LEDpackage further comprises a light-transmissive submount that comprises afirst face and a second face that is opposite the first face, whereinthe at least one LED and the active electrical element are mounted onthe first face and the second face is a primary emission face of the LEDpackage.

In another aspect, an LED package comprises: at least one LED; and anactive electrical element electrically connected to the at least oneLED, the active electrical element configured to drive the at least oneLED and switch between a forward bias state and a reverse bias state forthe at least one LED. In certain embodiments, the active electricalelement further comprises a level sensor that is configured to providean error signal while the at least one LED is in the reverse bias state.In certain embodiments, the active electrical element further comprisesan analog-to-digital converter that is configured to provide reverseleakage measurements while the at least one LED is in the reverse biasstate. In certain embodiments, the analog-to-digital converter comprisesat least one of an analog filter circuit and digital filter circuitry.In certain embodiments, the analog-to-digital converter is configured todetect a voltage relating to an operating condition of the at least oneLED while the at least one LED is in the reverse bias state. In certainembodiments, the analog-to-digital converter is configured to detect avoltage relating to an operating condition of the at least one LED whilethe at least one LED is in the forward bias state. In certainembodiments, the active electrical element is configured to adjust adrive signal of the at least one LED based on the voltage detected whilethe at least one LED is in the forward bias state. In certainembodiments, the drive signal comprises a pulse width modulation signaland the active electrical element is configured to adjust a pulse widthmodulation duty cycle of the at least one LED. In certain embodiments,the active electrical element comprises a resistor network that providespredetermined current limits to the at least one LED. In certainembodiments, the active electrical element comprises a current sourcethat provides an adjustable current to the at least one LED. In certainembodiments, the active electrical element comprises an inverter that isconfigured to provide the reverse bias state. In certain embodiments,the active electrical element is configured to communicate with andrespond to commands from another control element. In certainembodiments, the active electrical element is configured to receive datavalues and transform the data values according to a transfer function.In certain embodiments, the active electrical element is configured toreceive selectable color depth data. In certain embodiments, the activeelectrical element comprises at least two bidirectional communicationports. In certain embodiments, the LED package further comprises alight-transmissive submount that comprises a first face and a secondface that is opposite the first face, wherein the at least one LED andthe active electrical element are mounted on the first face and thesecond face is a primary emission face of the LED package.

In another aspect, an LED package comprises: at least one LED; and anactive electrical element electrically connected to the at least oneLED, the active electrical element comprising at least oneanalog-to-digital converter. In certain embodiments, the at least oneanalog-to-digital converter is configured to detect a voltage relatingto reverse leakage measurements of the at least one LED while the atleast one LED is in a reverse bias state. In certain embodiments, the atleast one analog-to-digital converter is configured to detect a voltagerelating to forward voltage measurements of the at least one LED. Incertain embodiments, the at least one analog-to-digital converter isconfigured to detect an electrical short condition of the at least oneLED. In certain embodiments, the at least one analog-to-digitalconverter is configured to detect an electrical open condition of the atleast one LED. In certain embodiments, the active electrical element isconfigured to adjust a pulse width modulation duty cycle of the at leastone LED based on voltage levels that are detected by the at least oneanalog-to-digital converter. In certain embodiments, the at least oneanalog-to-digital converter is configured to transmit measured data fromthe at least one LED to the active electrical element for serial output.In certain embodiments, the at least one ADC is configured to provide atleast one of reverse leakage measurements and forward voltagemeasurements for a plurality of LEDs. In certain embodiments, the atleast one ADC is configured to provide temperature measurements bymeasuring a voltage provided by a thermal sensor. In certainembodiments, the active electrical element is configured to drive the atleast one LED and switch between a forward bias state and a reverse biasstate for the at least one LED. In certain embodiments, the activeelectrical element is configured to receive data values and transformthe data values according to a transfer function. In certainembodiments, the active electrical element is configured to receiveselectable color depth data. In certain embodiments, the activeelectrical element further comprises at least two bidirectionalcommunication ports. In certain embodiments, the LED package furthercomprises a light-transmissive submount that comprises a first face anda second face that is opposite the first face, wherein the at least oneLED and the active electrical element are mounted on the first face andthe second face is a primary emission face of the LED package.

In another aspect, an LED package comprises: at least one LED; and anactive electrical element electrically connected to the at least oneLED, the active electrical element configured to receive selectablecolor depth data. In certain embodiments, the selectable color depthdata is in a range including 1-bit color depth to 100-bit color depth.In certain embodiments, the selectable color depth data is selectablefrom any one of 24-bit, 30-bit, 36-bit, and 48-bit color depths. Incertain embodiments, a particular bit depth is achieved by selecting anext-higher bit depth and zero-padding a number of least significantbits relating to the difference. In certain embodiments, the activeelectrical element is configured to receive data values and transformthe data values according to a transfer function. In certainembodiments, the active electrical element is configured to drive the atleast one LED and switch between a forward bias state and a reverse biasstate for the at least one LED. In certain embodiments, the activeelectrical element comprises at least two bidirectional communicationports. In certain embodiments, the LED package further comprises alight-transmissive submount that comprises a first face and a secondface that is opposite the first face, wherein the at least one LED andthe active electrical element are mounted on the first face and thesecond face is a primary emission face of the LED package.

In another aspect, an LED package comprises: at least one LED; and anactive electrical element electrically connected to the at least oneLED, the active electrical element configured to run a self-checkroutine that provides an at least one output signal indicating at leastone of a passing or failing condition for the at least one LED. Incertain embodiments, the at least one passing or failing conditioncomprises a forward voltage requirement of the at least one LED. Incertain embodiments, the at least one passing or failing conditioncomprises a reverse leakage requirement of the at least one LED. Incertain embodiments, the self-check routine provides a temperatureassessment for the at least one LED. In certain embodiments, the activeelectrical element is configured to run the self-check routine at powerstart-up. In certain embodiments, the active electrical element isconfigured to run the self-check routine when directly connected to apower source. In certain embodiments, the at least one output signal iscommunicated to an electrical port. In certain embodiments, the at leastone output signal is communicated as an optical signal by the at leastone LED. In certain embodiments, the optical signal comprises blinkingthe at least one LED according to one or more of predetermined colors,durations, and counts. In certain embodiments, the optical signal isconfigured to provide high speed communication followed by low speedcommunication and only the low speed communication compriseshuman-readable code. In certain embodiments, the self-check routine isconfigured to provide a time delay before the low speed communicationsuch that the self-check routine can be aborted before transmitting thelow-speed communication.

In another aspect, an LED package comprises: at least one LED; an activeelectrical element electrically connected to the at least one LED; and aplurality of polarity-agnostic connection ports that are connected tothe active electrical element. In certain embodiments, each one of theplurality of polarity-agnostic inputs is capable of connecting with oneof a supply voltage input, a ground input, a communication input, and acommunication output. In certain embodiments, the active electricalelement further comprises an active switching network that is connectedto the plurality of polarity-agnostic connection ports. In certainembodiments, the active electrical element further comprises at leasttwo bidirectional communication ports connected to the active switchingnetwork. In certain embodiments, the plurality of polarity-agnosticconnection ports are package bond pads of the LED package.

In another aspect, any of the foregoing aspects, and/or various separateaspects and features as described herein, may be combined for additionaladvantage. Any of the various features and elements as disclosed hereinmay be combined with one or more other disclosed features and elementsunless indicated to the contrary herein.

Those skilled in the art will appreciate the scope of the presentdisclosure and realize additional aspects thereof after reading thefollowing detailed description of the preferred embodiments inassociation with the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawing figures incorporated in and forming a part ofthis specification illustrate several aspects of the disclosure, andtogether with the description serve to explain the principles of thedisclosure.

FIG. 1A is a top view of a front face of a representative display panelfor a light emitting diode (LED) display that includes a plurality ofactive LED pixels.

FIG. 1B is a bottom view of a back face of the representative displaypanel of FIG. 1A.

FIG. 2A is a bottom view of an LED package at a particular state offabrication where a plurality of LEDs and an active electrical elementare mounted on a submount.

FIG. 2B is a cross-sectional view taken along the section line A-A ofFIG. 2A.

FIG. 2C is a bottom view of the LED package of FIG. 2A at a subsequentstate of fabrication where an encapsulant layer and a plurality ofelectrically conductive traces have been formed.

FIG. 2D is a cross-sectional view taken along the section line B-B ofFIG. 2C.

FIG. 2E is a bottom view of the LED package of FIG. 2C at a subsequentstate of fabrication where an additional encapsulant layer and aplurality of package bond pads have been formed.

FIG. 2F is a cross-sectional view taken along the section line C-C ofFIG. 2E.

FIG. 2G is a cross-sectional view taken along the section line D-D ofFIG. 2E.

FIG. 2H is a simplified top view of the LED package of FIG. 2E.

FIG. 2I is a simplified bottom view of the LED package of FIG. 2E.

FIG. 3A is a bottom view of a representative LED package that includes aplurality of electrically conductive traces where portions of certainones of the electrically conductive traces form package bond pads forthe LED package.

FIG. 3B is a cross-sectional view taken along the section line E-E ofFIG. 3A.

FIG. 4 is a cross-sectional view of an LED package illustratingconfigurations where one or more LED chips and an active electricalelement are mounted along a same horizontal plane.

FIG. 5 is a cross-sectional view of an LED package illustratingconfigurations where one or more LED chips are mounted along a firsthorizontal plane and an active electrical element is mounted along asecond horizontal plane that is different than the first horizontalplane.

FIG. 6 is a cross-sectional view of an LED package illustratingconfigurations where one or more LED chips and an active electricalelement are mounted to opposing faces of the submount.

FIG. 7 is a bottom view of an LED package that includes a plurality ofLED pixels according to embodiments disclosed herein.

FIG. 8 is a block diagram schematic illustrating components of an activeelectrical element according to embodiments disclosed herein.

FIG. 9 is a block diagram schematic illustrating components of an activeelectrical element according to embodiments disclosed herein.

FIG. 10 is a schematic diagram illustrating an exemplary structure forvolatile memory elements that may be included within active electricalelements according to embodiments disclosed herein.

FIG. 11A is a schematic diagram illustrating a driver element thatincludes a voltage controlled current source circuit.

FIG. 11B is a schematic diagram illustrating a driver element thatincludes a transconductance amplifier arranged with an active cascodeconfiguration

FIG. 11C is a schematic diagram illustrating a driver element thatincludes an input amplifier added to the driver element of FIG. 11B.

FIG. 11D is a schematic diagram illustrating a driver element that issimilar to the driver element of FIG. 11C, but with flipped polarityconnections.

FIG. 11E is a schematic diagram illustrating a driver element thatincludes a Howland current pump.

FIG. 11F is a schematic diagram illustrating a driver element that issimilar to the driver element of FIG. 11E and adds a voltage divider andan additional operational amplifier.

FIG. 12A is a block diagram schematic illustrating an embodiment of anactive electrical element that includes a detector element.

FIG. 12B is a bottom view of an LED package that includes a photodiodeaccording to embodiments disclosed herein.

FIG. 13 is block diagram schematic illustrating various components thatmay be included in a system level control scheme for an LED displaypanel according to embodiments disclosed herein.

FIG. 14 is a schematic illustration representing a configuration wherean active electrical element corresponding to a particular LED pixel isconfigured to receive a row select signal line as well as separatecontrol signals for each red, green, and blue LED chips that areincluded within the LED pixel.

FIG. 15 is a schematic illustration representing a configuration wherean active electrical element corresponding with a particular LED pixelis configured to receive a separate row select signal line for each LEDchip of the LED pixel and a single color level signal line for all ofthe LED chips within the LED pixel.

FIG. 16 is a schematic illustration representing a configuration wherean active electrical element corresponding with a particular LED pixelis configured to receive encoded row select signals for each LED chip ofthe LED pixel and a single color level signal line for all of the LEDchips within the LED pixel.

FIG. 17 is a schematic illustration representing a configuration wherean active electrical element of a particular LED package is configuredto receive a row select signal, a color level signal, and one or morecolor select signals for red, green, and blue LED chips that areincluded within the LED package.

FIG. 18 is a schematic illustration representing an independent notationconfiguration that is similar to both the configurations of FIG. 16 andFIG. 17 .

FIG. 19 is a schematic illustration representing a configuration wherean active electrical element corresponding with a particular LED pixelis configured to receive a single row select signal line and a singlecolor level signal line for all LED chips of the LED pixel.

FIG. 20 is a schematic illustration representing a configuration wherean active electrical element corresponding with a particular LED pixelis configured to receive a single row select signal line and a singlecolor level signal line for all LED chips of the LED pixel.

FIG. 21 is a block diagram schematic illustrating a system level controlscheme for an LED display panel where each active electrical element ofan LED pixel array is configured to receive signal lines according tothe embodiment of FIG. 20 .

FIG. 22 is a partial plan view illustrating a routing configuration foran LED display panel that is configured for operation according to theconfigurations of FIG. 20 and FIG. 21 .

FIG. 23 is a schematic illustration representing a configuration wherean active electrical element corresponding with a particular LED pixelis configured to receive all-digital communication for row, column,and/or color select signals.

FIG. 24 is a block diagram schematic illustrating a system level controlscheme for an LED display panel where each active electrical element ofan LED pixel array is configured to receive signal lines according tothe embodiment of FIG. 23 .

FIG. 25 is a partial plan view illustrating a routing configuration foran LED display panel that is configured for operation according to theconfiguration of FIG. 23 .

FIGS. 26A and 26B are schematic diagrams illustrating arrangements of anexemplary data packet according to embodiments disclosed herein.

FIG. 27 is a schematic diagram illustrating a cascading flow of datapackets from a control element to a plurality of LED packages accordingto embodiments disclosed herein.

FIG. 28 is a schematic diagram illustrating a cascading flow of datapackets from a control element to a plurality of LED packages and a flowof one or more talk-back data packets to the control element accordingto embodiments disclosed herein.

FIG. 29 is a schematic diagram illustrating a cascading flow of datapackets from a control element that additionally includes data packetsthat are configured to provide information to all LED packages accordingto embodiments disclosed herein.

FIG. 30 is a schematic diagram illustrating a cascading flow of datapackets from a control element that additionally includes one or morecontinuation data packets that are configured to provide additionalinformation to at least one LED package according to embodimentsdisclosed herein.

FIG. 31 is a partial plan view illustrating a routing configuration foran LED panel that is configured for operation according to embodimentsdisclosed herein.

FIG. 32 is a partial plan view illustrating a routing configuration foran LED panel that includes LED packages with selectively assignablecommunication ports according to embodiments disclosed herein.

FIG. 33 is a partial plan view illustrating another routingconfiguration for an LED panel that includes LED packages withselectively assignable communication ports according to embodimentsdisclosed herein.

FIG. 34 is a partial plan view illustrating the routing configurationfor the LED panel of FIG. 33 with the addition of voltage lines andground lines according to embodiments disclosed herein.

FIG. 35 is a schematic diagram illustrating various inputs andcorresponding actions for active electrical elements according toembodiments disclosed herein.

FIG. 36 is a schematic diagram illustrating an active electrical elementcomprising a finite state machine according to embodiments disclosedherein.

FIG. 37 is a schematic diagram illustrating embodiments where an activeelectrical element is configured to detect normal or adverse operatingconditions of at least one LED according to embodiments disclosedherein.

FIG. 38 is a schematic diagram illustrating embodiments where an activeelectrical element is configured to provide both forward and reversebias states to at least one LED according to embodiments disclosedherein.

FIG. 39 is a schematic diagram illustrating embodiments where theresistor network and corresponding selection switches of FIG. 38 arereplaced with a current source according to embodiments disclosedherein.

FIG. 40 is a schematic diagram illustrating multiple LED embodimentssimilar to the schematic diagram of FIG. 39 .

FIG. 41 is a schematic diagram illustrating the active electricalelement of FIG. 40 configured with multiple ports that include supplyvoltage, ground, and bidirectional communication ports according toembodiments disclosed herein.

FIG. 42 is a schematic diagram illustrating the active electricalelement of FIG. 41 configured with polarity-agnostic input capabilitiesaccording to embodiments disclosed herein.

FIG. 43 is a schematic diagram illustrating a four-input rectifier thatmay be that may be used to provide initial power to a switching networkof FIG. 42 .

DETAILED DESCRIPTION

The embodiments set forth below represent the necessary information toenable those skilled in the art to practice the embodiments andillustrate the best mode of practicing the embodiments. Upon reading thefollowing description in light of the accompanying drawing figures,those skilled in the art will understand the concepts of the disclosureand will recognize applications of these concepts not particularlyaddressed herein. It should be understood that these concepts andapplications fall within the scope of the disclosure and theaccompanying claims.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present disclosure. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element such as a layer, region, orsubstrate is referred to as being “on” or extending “onto” anotherelement, it can be directly on or extend directly onto the other elementor intervening elements may also be present. In contrast, when anelement is referred to as being “directly on” or extending “directlyonto” another element, there are no intervening elements present.Likewise, it will be understood that when an element such as a layer,region, or substrate is referred to as being “over” or extending “over”another element, it can be directly over or extend directly over theother element or intervening elements may also be present. In contrast,when an element is referred to as being “directly over” or extending“directly over” another element, there are no intervening elementspresent. It will also be understood that when an element is referred toas being “connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present.

Relative terms such as “below” or “above” or “upper” or “lower” or“horizontal” or “vertical” or “top” or “bottom” or “row” or “column” maybe used herein to describe a relationship of one element, layer,surface, or region to another element, layer, surface or region asillustrated in the Figures. It will be understood that these terms andthose discussed above are intended to encompass different orientationsof the device in addition to the orientation depicted in the Figures.For example, if the apparatus in a particular Figure is turn over, anelement, layer, surface or region described as “above” would now beoriented as “below.”

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes,” and/or “including” when used herein specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms used herein should be interpreted ashaving a meaning that is consistent with their meaning in the context ofthis specification and the relevant art and will not be interpreted inan idealized or overly formal sense unless expressly so defined herein.

The present disclosure relates to light emitting diodes (LEDs), LEDpackages, and related LED displays, and more particularly to activecontrol of LEDs within LED displays. LED displays may include rows andcolumns of LEDs that form an array of LED pixels. A particular LED pixelmay include a cluster of LED chips of the same color or multiple colors,with an exemplary LED pixel including a red LED chip, a green LED chip,and a blue LED chip. In certain embodiments, an LED package includes aplurality of LED chips that form at least one LED pixel and a pluralityof such LED packages may be arranged to form an array of LED pixels foran LED display. Each LED package may include an active electricalelement that is configured to receive a control signal and activelymaintain an operating state, such as brightness or grey level, or acolor select signal for the LED chips of the LED package while other LEDpackages are being addressed. In certain embodiments, the activeelectrical element may include active circuitry that includes one ormore of a driver device, a signal conditioning or transformation device,a memory device, a decoder device, an electrostatic discharge (ESD)protection device, a thermal management device, and a detection device,among others. In this regard, each LED pixel of an LED display may beconfigured for operation with active matrix addressing. The activeelectrical element may be configured to receive one or more of an analogcontrol signal, an encoded analog control signal, a digital controlsignal, and an encoded digital control signal. Display panels aredisclosed that include an array of such LED pixels on a first face of apanel and control circuitry on a backside of the panel that isconfigured to communicate with each active electrical element of the LEDpixels.

LED packages are disclosed that are configured to receive a data streamthat includes a plurality of data packets. Each data packet may includean identifier that enables each LED package of an array that receivesthe data packet to take one or more actions based on the identifier or aseries of identifiers. Various additional data packets are disclosedincluding talk-back data packets, data packets for all LED packages thatreceive a data stream, and continuation data packets. LED packages withselectively assignable communication ports are also disclosed. Datasignals and data packets sent to active electrical elements may includecompressed data codes that are subsequently decompressed, and one ormore of transfer functions, gamma correction, and color depth data.Active electrical elements are disclosed that are configured to provideboth forward and reverse bias states to LEDs in order to detect adverseoperating conditions such as reverse leakage and deviations to forwardvoltage levels. Such adverse operating conditions may be performed aspart of a self-check routine for an LED package. Active electricalelements as disclosed herein may comprise analog-to-digital converters(ADCs). LED packages are also disclosed that may self-configure based onthe manner in which various input or output lines are connected.

An LED chip typically comprises an active LED structure or region thatcan have many different semiconductor layers arranged in different ways.The fabrication and operation of LEDs and their active structures aregenerally known in the art and are only briefly discussed herein. Thelayers of the active LED structure can be fabricated using knownprocesses with a suitable process being fabrication using metal organicchemical vapor deposition. The layers of the active LED structure cancomprise many different layers and generally comprise an active layersandwiched between n-type and p-type oppositely doped epitaxial layers,all of which are formed successively on a growth substrate. It isunderstood that additional layers and elements can also be included inthe active LED structure, including but not limited to, buffer layers,nucleation layers, super lattice structures, un-doped layers, claddinglayers, contact layers, current-spreading layers, and light extractionlayers and elements. The active layer can comprise a single quantumwell, a multiple quantum well, a double heterostructure, or superlattice structures.

The active LED structure can be fabricated from different materialsystems, with some material systems being Group III nitride-basedmaterial systems. Group III nitrides refer to those semiconductorcompounds formed between nitrogen and the elements in Group III of theperiodic table, usually aluminum (Al), gallium (Ga), and indium (In).Gallium nitride (GaN) is a common binary compound. Group III nitridesalso refer to ternary and quaternary compounds such as aluminum galliumnitride (AlGaN), indium gallium nitride (InGaN), and aluminum indiumgallium nitride (AlInGaN). For Group III nitrides, silicon (Si) is acommon n-type dopant and magnesium (Mg) is a common p-type dopant.Accordingly, the active layer, n-type layer, and p-type layer mayinclude one or more layers of GaN, AlGaN, InGaN, and AlInGaN that areeither undoped or doped with Si or Mg for a material system based onGroup III nitrides. Other material systems include silicon carbide(SiC), organic semiconductor materials, and other Group III-V systemssuch as gallium phosphide (GaP), gallium arsenide (GaAs), and relatedcompounds.

The active LED structure may be grown on a growth substrate that caninclude many materials, such as sapphire, SiC, aluminum nitride (AlN),GaN, with a suitable substrate being a 4H polytype of SiC, althoughother SiC polytypes can also be used including 3C, 6H, and 15Rpolytypes. SiC has certain advantages, such as a closer crystal latticematch to Group III nitrides than other substrates and results in GroupIII nitride films of high quality. SiC also has a very high thermalconductivity so that the total output power of Group III nitride deviceson SiC is not limited by the thermal dissipation of the substrate.Sapphire is another common substrate for Group III nitrides and also hascertain advantages, including being lower cost, having establishedmanufacturing processes, and having good light transmissive opticalproperties.

Different embodiments of the active LED structure can emit differentwavelengths of light depending on the composition of the active layerand n-type and p-type layers. For example, the active LED structure forvarious LEDs may emit blue light with a peak wavelength range ofapproximately 430 nanometers (nm) to 480 nm, green light with a peakwavelength range of 500 nm to 570 nm, or red light with a peakwavelength range of 600 nm to 650 nm. The LED chip can also be coveredwith one or more lumiphoric or other conversion materials, such asphosphors, such that at least some of the light from the LED chip isabsorbed by the one or more phosphors and is converted to one or moredifferent wavelength spectra according to the characteristic emissionfrom the one or more phosphors. In some embodiments, the combination ofthe LED chip and the one or more phosphors emits a generally whitecombination of light. The one or more phosphors may include yellow(e.g., YAG:Ce), green (e.g., LuAg:Ce), and red (e.g.,Ca_(i-k-y)Sr_(x)Eu_(y)AlSiN₃) emitting phosphors, and combinationsthereof. Lumiphoric materials as described herein may be or include oneor more of a phosphor, a scintillator, a lumiphoric ink, a quantum dotmaterial, a day glow tape, and the like. Lumiphoric materials may beprovided by any suitable means, for example, direct coating on one ormore surfaces of an LED, dispersal in an encapsulant material configuredto cover one or more LEDs, and/or coating on one or more optical orsupport elements (e.g., by powder coating, inkjet printing, or thelike). In certain embodiments, lumiphoric materials may bedownconverting or upconverting, and combinations of both downconvertingand upconverting materials may be provided. In certain embodiments,multiple different (e.g., compositionally different) lumiphoricmaterials arranged to produce different peak wavelengths may be arrangedto receive emissions from one or more LED chips.

Light emitted by the active layer or region of the LED chip typicallyhas a lambertian emission pattern. For directional applications,internal mirrors or external reflective surfaces may be employed toredirect as much light as possible toward a desired emission direction.Internal mirrors may include single or multiple layers. Some multi-layermirrors include a metal reflector layer and a dielectric reflectorlayer, wherein the dielectric reflector layer is arranged between themetal reflector layer and a plurality of semiconductor layers. Apassivation layer may be arranged between the metal reflector layer andfirst and second electrical contacts, wherein the first electricalcontact is arranged in conductive electrical communication with a firstsemiconductor layer, and the second electrical contact is arranged inconductive electrical communication with a second semiconductor layer.In some embodiments, the first and second electrical contacts themselvesmay be configured as mirror layers. For single or multi-layer mirrorsincluding surfaces exhibiting less than 100% reflectivity, some lightmay be absorbed by the mirror. Additionally, light that is redirectedthrough the active LED structure may be absorbed by other layers orelements within the LED chip.

As used herein, a layer or region of a light-emitting device may beconsidered to be “transparent” when at least 80% of emitted radiationthat impinges on the layer or region emerges through the layer orregion. Moreover, as used herein, a layer or region of an LED isconsidered to be “reflective” or embody a “mirror” or a “reflector” whenat least 80% of the emitted radiation that impinges on the layer orregion is reflected. In some embodiments, the emitted radiationcomprises visible light such as blue and/or green LEDs with or withoutlumiphoric materials. In other embodiments, the emitted radiation maycomprise nonvisible light. For example, in the context of GaN-based blueand/or green LEDs, silver (for example, at least 80% reflective) may beconsidered a reflective material. In the case of ultraviolet (UV) LEDs,appropriate materials may be selected to provide a desired, and in someembodiments high reflectivity; and/or a desired, and in some embodimentslow, absorption. In certain embodiments, a “light-transmissive” materialmay be configured to transmit at least 50% of emitted radiation of adesired wavelength. In certain embodiments, an initially“light-transmissive” material may be altered to be a “light-absorbingmaterial” that transmits less than 50% of emitted radiation of a desiredwavelength with the addition of one or more light-absorbing materials,such as opaque or non-reflective materials including grey, dark, orblack particles or materials.

The present disclosure can be useful for LED chips having a variety ofgeometries, such as vertical geometry or lateral geometry. A verticalgeometry LED chip typically includes anode and cathode connections onopposing sides of the LED chip. A lateral geometry LED chip typicallyincludes both anode and cathode connections on the same side of the LEDchip that is opposite a substrate, such as a growth substrate. Certainembodiments disclosed herein relate to the use of flip chip LED devicesin which a light transmissive substrate represents an exposed lightemitting surface.

LED chips or LED packages that include one or more LED chips can bearranged in many different applications to provide illumination ofobjects, surfaces, or areas. In certain applications, clusters ofdifferently colored LED chips or LED packages may be arranged as pixelsfor LED display applications, including video displays. For example,individual clusters of red, green, and blue LED chips may form LEDpixels of a larger LED display. In certain applications, the red, green,and blue LED chips of each pixel may be packaged together as amultiple-LED package and the LED display is formed when arrays of suchmultiple-LED packages are arranged together. In this regard, each pixelmay include a single LED package that includes a red LED chip, a greenLED chip, and a blue LED chip. In other embodiments, the red, green, andblue LED chips may be separately packaged or arranged in a chip-on-boardconfiguration. In certain LED display applications, arrays of LED pixelsare arranged on panels, which may also be referred to as tiles or LEDmodules, and arrays of such panels are arranged together to form largerLED displays. Depending on the application, each panel of an LED displaymay include different numbers of LED pixels. In certain applications,each panel of an LED display may include an array formed by 64 rows by64 columns of LED pixels or more. In certain embodiments, each panel ofan LED display may be configured with a horizontal display resolution ofabout 4,000 LED pixels, or 4K resolution. For applications where higherscreen resolution is desired for LED displays, each panel may includeeven more rows and columns of LED pixels that are more closely spaced toone another. Depending on the desired screen resolution, pixel pitchesmay be about 3 millimeters (mm), or about 2.5 mm, or about 1.6 mm, or ina range from about 1.5 mm to about 3 mm, or in a range from about 1.6 mmto about 3 mm, or in a range from about 1.5 mm to about 2.5 mm.Additionally, for fine pitch LED displays with even higher screenresolutions, pixel pitches may be configured to be less than 1 mm, orless than 0.8 mm, or in a range from about 0.5 mm to about 1 mm, orabout 0.7 mm for certain embodiments.

In conventional video display applications, the LED pixels are typicallyconfigured for passive matrix addressing. In this regard, the LED pixelsmay be arranged for coupling to a passive interface element thatprovides electrical connections to a separate driver or controller. Forexample, orthogonally arranged (e.g., vertical and horizontal)conductors form rows and columns in a grid pattern, whereby individualLED chips of each LED pixel are defined by each intersection of a rowand column. Multiplex sequencing may be used to permit individualcontrol of each LED chip of the array while employing a smaller numberof conductors than the number of LED chips in the array, either byutilizing a common-row anode or common-row cathode matrix arrangement,and brightness control may be provided by pulse width modulation. Inthis manner, conductors for rows or columns are shared among many LEDpixels and time division multiplexing is employed to address eachindividual LED pixel. Due to their passive configuration, each LED pixelonly emits light within their respective communication times. Theseparate drivers for controlling the display are typically arrangedremotely from the pixels of the display, such as on a separate board ormodule, or on a printed circuit board (PCB) that is attached orotherwise mounted to the backside of each panel, or on the backside of acommon PCB that includes an array of pixels on the frontside. Aspreviously, described, the PCBs are typically densely populated withelectrical devices including capacitors, field effect transistors(FETs), decoders, microcontrollers, and the like for driving each of thepixels on a particular panel. For higher resolution displays, thedensity of such electrical devices scales higher corresponding to theincreased number of pixels on each panel. As previously described, thiscan add higher complexity and costs to LED panels for displayapplications as well as increase thermal crowding in areas where driverelectronics are more closely spaced. For passive matrix addressing, theLED pixels are typically driven by pulsed signal sequences. In thisregard, the LED pixels may pulse rapidly at certain frequencies, such as60 hertz (Hz) or 120 Hz depending on the display scan rate. While thevideo display may not appear to be rapidly pulsing to a human eye, itmay be detectable with image capture equipment, and in some instances,interference beating can be present between the video display and otherpulsed displays or light sources that are in proximity with the videodisplay.

According to embodiments disclosed herein, each LED pixel of an LEDdisplay may be configured for operation with active matrix addressing.For active matrix addressing, each LED pixel is configured to activelymaintain an operating or driving state, such as brightness or greylevel, or color select, while other LED pixels are being addressed,thereby allowing each LED pixel to maintain their driving state witheither reduced pulsing or no pulsing depending on the drivingconfiguration. Accordingly, each LED pixel may be configured to hold itsrespective operating state with a continuous drive signal, rather thanby pulsed signals associated with passive matrix addressing. In thisregard, each LED pixel may include an active electrical chip or anactive electrical element that may include a memory device and theability to alter a driving condition or drive condition of the LED pixelbased on a memory from the memory device. In certain embodiments, thecontinuous drive signal is a constant analog drive current, and in otherembodiments where the brightness level may be controlled by pulsedmethods such as pulse width modulation (PWM), the continuous drivesignal may refer to a PWM signal that is not interrupted by the scanningof other LED pixels within the array or within a sub-array. In certainembodiments, the active electrical chip may include active circuitrythat includes one or more of a driver device, a signal conditioning ortransformation device, a memory device, a decoder device, an ESDprotection device, a thermal management device, and a detection device,among others. As used herein, the term “active electrical chip,” “activeelectrical element,” or “active electrical component” includes any chipor component that is able to alter a driving condition of an LED basedon memory or other information that may be stored within a chip orcomponent. As used herein, the term “active LED pixel” includes one ormore LED devices that form a pixel and an active electrical chip asdescribed above. In certain embodiments, each LED pixel may comprise asingle LED package that is configured as an active LED package thatincludes multiple LED chips and an active electrical element asdescribed above. In this manner, the number of separate electricaldevices needed for the LED display may be reduced, such as the separateelectrical devices located on the backsides of LED panels of the LEDdisplay as previously described. Additionally, overall operating powersneeded to run the LED panels may be reduced.

FIG. 1A is a top view of a front face of a representative display panel10 for an LED display that includes a plurality of active LED pixels 12.As illustrated, the plurality of active LED pixels 12 may be arranged inrows and columns to form an array of active LED pixels 12 across thefront face of the display panel 10. In certain embodiments, each of theactive LED pixels 12 are configured with an active electrical elementthat includes the ability to receive an input signal, store a memorybased on the input signal, alter a driving condition of LEDs within eachactive LED pixel 12 based on the stored memory, and update the drivingcondition each time the memory is updated by the input signal. Incertain embodiments, each active LED pixel 12 comprises an LED packagethat includes a plurality of LED chips that form a LED pixel and theactive electrical element. FIG. 1B is a bottom view of a back face ofthe representative display panel 10 of FIG. 1A. All illustrated, thedisplay panel 10 may include additional passive or active elements thatare configured to receive, process, and distribute signals to the activeLED pixels (12 of FIG. 1A). For example, the display panel 10 mayinclude an input signal connector 14 and an output signal connector 16,each of which may be configured as a video source connector, including avideo graphics array (VGA) connector, a digital visual interface (DVI)connector, a high-definition multimedia interface (HDMI) connector, or aDisplayPort connector, among others. The display panel 10 may comprise acontrol element 18 that includes control circuitry, such as asemiconductor control element. The control element 18 may be configuredto receive an input signal via the input signal connector 14 and outputcontrol signals for the active LED pixels. As will later be described inmore detail, the active electrical element of each LED pixel isconfigured to independently alter a driving condition of each LED chipwithin the LED pixel in response to the control signals that areoutputted from the control element 18. In certain embodiments, thecontrol element 18 comprises an integrated circuit, such as one or moreof an application-specific integrated circuit (ASIC), a microcontroller,a programmable control element, and a field-programmable gate array(FPGA). In certain embodiments, a plurality of control elements 18 maybe configured on or registered with each display panel 10. A decoderelement 20 may be configured to receive and route the control signalsfrom the control element 18 to a plurality of signal lines for theactive LED pixels (12 of FIG. 1A). In certain embodiments, one or moredigital-to-analog converters (DACs) 22 may be provided to convertdigital signals from the control element 18 and the decoder element 20before reaching the active LED pixels (12 of FIG. 1A). The display panel10 may also include other passive or active elements 24, which mayinclude additional decoders, resistors, capacitors, or other electricalelements or circuits for video displays. In this manner, the signalconnectors 14 and 16, the control element 18, the decoder element 20,the DACs 22, and the other passive or active elements 24 are registeredwith the display panel 10. In alternative embodiments, the back face ofthe display panel 10 may comprise another plurality of LED packages thatform another array of LED pixels. In this regard, the display panel 10may be configured for a double-sided display application. In suchembodiments, at least some of the signal connectors 14 and 16, thecontrol element 18, the decoder element 20, the DACs 22, and the otherpassive or active elements 24 may be registered with the display panel10 in locations other than the back face in configurations to providecontrol signals from one or more edges of the display panel 10.

FIGS. 2A-2I illustrate various states of fabrication for an LED package26 that includes a plurality of LEDs 28-1 to 28-3 and an activeelectrical element 30 according to embodiments disclosed herein. Incertain embodiments, separate LED packages 26 may be configured to formeach of the active LED pixels (12 of FIG. 1A) in a display panel (10 ofFIG. 1A). The active electrical element 30 may also be referred to as anactive electrical chip or an active electrical component. FIG. 2A is abottom view of the LED package 26 at a particular state of fabricationwhere the plurality of LEDs 28-1 to 28-3 and the active electricalelement 30 are mounted on a submount 32. In particular, the plurality ofLEDs 28-1 to 28-3 and the active electrical element 30 may be mounted ona first face 32′ of the submount 32. A light transmissive die attachmaterial may be arranged between the plurality of LEDs 28-1 to 28-3 andthe submount 32 to facilitate mounting. Each of the plurality of LEDs28-1 to 28-3 may include a corresponding cathode contact 34-1 to 34-3(e.g., an n-type contact pad) and a corresponding anode contact 36-1 to36-3 (e.g., a p-type contact pad). In certain embodiments, the pluralityof LEDs 28-1 to 28-3 comprise individual LED chips that generatedifferent dominant wavelengths of light. For example, the LED 28-1 maybe configured to generate predominantly green emissions, the LED 28-2may be configured to generate predominantly blue emissions, and the LED28-3 may be configured to generate predominantly red emissions.Accordingly, the plurality of LEDs 28-1 to 28-3 may comprise a green LEDchip, a blue LED chip, and a red LED chip. In other embodiments,different combinations of colors and numbers of LEDs are possible. Instill further embodiments, each of the plurality of LEDs 28-1 to 28-3may be configured to generate light emissions that are predominantly thesame as one another. In other embodiments, the plurality of LEDs 28-1 to28-3 may comprise a micro-LED structure where a common active LEDstructure is segregated into a plurality of active LED structureportions to form the plurality of LEDs 28-1 to 28-3 that may beindependently addressable from one another.

In certain embodiments, the active electrical element 30 is configuredto receive a signal or a plurality of signals and independently driveeach LED of the plurality of LEDs 28-1 to 28-3. In certain embodiments,the active electrical element 30 includes a memory element, chip, orcomponent that is configured to store one or more operating states forthe plurality of LEDs 28-1 to 28-3 that are received from an externalsource, such as the control element (18 of FIG. 1B). The activeelectrical element 30 may further be configured to alter one or moredriving conditions of the plurality of LEDs 28-1 to 28-3 based on theone or more stored operating states. In certain embodiments, the activeelectrical element 30 is configured to independently alter a drivingcondition of each LED of the plurality of LEDs 28-1 to 28-3 based on aplurality of operating states that are stored by the memory element. Inthis regard, the active electrical element 30 may be configured toreceive and store one or more operating states, and independently driveeach LED of the plurality of LEDs 28-1 to 28-3 according to one or moreoperating states. The active electrical element 30 may continue to driveand maintain the operating state for each LED of the plurality of LEDs28-1 to 28-3 until the active electrical element 30 receives refreshedor updated signals that correspond to updated operating states. In thismanner, the active electrical element 30 may be configured to alter adriving condition of the plurality of LEDs 28-1 to 28-3 in accordance toa temporarily stored operating state of the memory element. Accordingly,the plurality of LEDs 28-1 to 28-3 may be configured for active matrixaddressing as previously described. In order to rapidly receive one ormore operating states for the plurality of LEDs 28-1 to 28-3, the activeelectrical element 30 may include a plurality of contact pads 38. Incertain embodiments, certain contact pads of the plurality of contactpads 38 are configured to receive one or more signals and other contactpads of the plurality of contact pads 38 are configured to send signalsto independently drive or address the plurality of LEDs 28-1 to 28-3. Incertain embodiments, the active electrical element 30 comprises one ormore of an integrated circuit chip, an ASIC, a microcontroller, or aFPGA. In certain embodiments, the active electrical element 30 may beconfigured to be programmable or reprogrammable after it is manufacturedthrough various memory elements and logic that are incorporated withinthe active electrical element 30. In this regard, the active electricalelement 30 may be considered programmable for embodiments where theactive electrical element 30 does not include a full FPGA.

The submount 32 can be formed of many different materials with apreferred material being electrically insulating. Suitable materialsinclude, but are not limited to ceramic materials such as aluminum oxideor alumina, AlN, or organic insulators like polyimide (PI) andpolyphthalamide (PPA). In other embodiments the submount 32 can comprisea PCB, sapphire, Si or any other suitable material. For PCB embodiments,different PCB types can be used such as standard FR-4 PCB,bismaleimide-triazine (BT), or related materials, metal core PCB, or anyother type of PCB. In certain embodiments, the submount 32 comprises alight-transmissive material such that light emissions from the pluralityof LEDs 28-1 to 28-3 may pass through the submount 32. In this regard, alight emitting face of each of the plurality of LEDs 28-1 to 28-3 may bemounted to the submount 32. Suitable light-transmissive materials forthe submount 32 include glass, sapphire, epoxy, and silicone. In certainembodiments where the submount 32 is a light-transmissive submount, thesubmount 32 may be referred to as a superstrate. The term “superstrate”is used herein, in part, to avoid confusion with other substrates thatmay be part of the semiconductor light emitting device, such as a growthor carrier substrate of an LED chip or a different submount for the LEDpackage 26. The term “superstrate” is not intended to limit theorientation, location, and/or composition of the structure it describes.In certain embodiments, the submount 32 may comprise alight-transmissive superstrate and the LED package 26 may be devoid ofanother submount. In other embodiments, the submount 32 may comprise alight-transmissive superstrate and the LED package 26 comprises anadditional submount, wherein the plurality of LEDs 28-1 to 28-3 arearranged between the submount 32 and the additional submount.

FIG. 2B is a cross-sectional view taken along the section line A-A ofFIG. 2A. As illustrated, the LED 28-1 is mounted to the first face 32′of the submount 32. Accordingly, emissions from the LED 28-1 may beconfigured to pass through the submount 32 such that a second face 32″of the submount 32 is configured as a primary emission face of the LEDpackage 26. Notably, the anode contact 36-1 and the cathode contact(34-1) of the LED 28-1 are arranged on an opposite side of the LED 28-1relative to the submount 32. In this regard, light emissions from theLED 28-1 may pass through the submount and out of the opposite face 32″without interacting or being absorbed by the anode contact 36-1 and thecathode contact (34-1). The orientation of the cross-sectional view inFIG. 2B is intended to illustrate that the second face 32″ of thesubmount 32 will be configured as the primary light emission face;however, during intermediate fabrication steps, the orientation of FIG.2B and subsequent cross-sectional fabrication views may be rotated 180degrees such that the LED 28-1 is assembled sequentially above thesubmount 32.

FIG. 2C is a bottom view of the LED package 26 of FIG. 2A at asubsequent state of fabrication where an encapsulant layer 40 and aplurality of electrically conductive traces 42-1 to 42-7 have beenformed. FIG. 2D is a cross-sectional view taken along the section lineB-B of FIG. 2C where an electrical connector 44 is visible. Beforeformation of the encapsulant layer 40 and the plurality of electricallyconductive traces 42-1 to 42-7, a plurality of electrical connectors 44may be formed over the cathode contacts 34-1 to 34-3 and the anodecontacts 36-1 to 36-3 of each of the plurality of LEDs 28-1 to 28-3. Theplurality of electrical connectors 44 may also be formed over theplurality of contact pads 38 of the active electrical element 30. Incertain embodiments, the plurality of electrical connectors 44 mayinclude at least one of a metal bump bond, a metal pad, a metal wire, ametal interconnect, and a metal pedestal, among others. The plurality ofelectrical connectors 44 may be formed by a variety of methods,including but not limited to, wire bump bonding, solder bumping,plating, laser drilling of vias that are subsequently filled with metal,or other metallization formation techniques. Electrical connectors 44may be formed at the wafer-level, before component assembly, after dieattach of the LEDs 28-1 to 28-3, or at other fabrication steps dependingupon various process configurations. After formation of the plurality ofelectrical connectors 44, the encapsulant layer 40 may be blanketdeposited to cover the plurality of LEDs 28-1 to 28-3 and the activeelectrical element 30. In certain embodiments, the encapsulant layer 40may further cover the plurality of electrical connectors 44. Theencapsulant layer 40 may be configured to surround perimeter or lateraledges of each LED of the plurality of LEDs 28-1 to 28-3. As illustratedin FIG. 2D, the encapsulant layer 40 may cover at least a portion of abottom surface of each LED of the plurality of LEDs 28-1 to 28-3. Theencapsulant layer 40 may also be configured to surround perimeter orlateral edges of the active electrical element 30. In such embodiments,a removal step may be subsequently applied to the encapsulant layer 40such that a portion of the encapsulant layer 40 is removed to formexposed surfaces of the plurality of electrical connectors 44. Theremoval step may comprise a planarizing process, such as grinding,lapping, or polishing the encapsulant layer 40 to expose the pluralityof electrical connectors 44. For embodiments, where the plurality ofelectrical connectors 44 comprise laser drilled vias or microvias, theremoval step may not be required.

The encapsulant layer 40 may be applied or deposited by a coating ordispensing process. In certain embodiments, the encapsulant layer 40 maycomprise one or more of a silicone, an epoxy, and a thermoplastic suchas polycarbonate, aliphatic urethane, or polyester, among others. Theencapsulant layer 40 may be configured to alter or control light outputfrom the plurality of LEDs 28-1 to 28-3. For example, the encapsulantlayer 40 may comprise an opaque or non-reflective material, such as agrey, dark, or black material that may absorb some light that travelsbetween the plurality of LEDs 28-1 to 28-3, thereby improving contrastbetween emissions of the plurality of LEDs 28-1 to 28-3 that passthrough the submount 32. In certain embodiments, the encapsulant layer40 may include light-absorbing particles suspended in a binder such assilicone or epoxy. The light-absorbing particles may include at leastone of carbon, silicon, or metal particles or nanoparticles. In certainembodiments, the light-absorbing particles comprise a predominantlyblack color that when suspended in the binder, provide a predominantlyblack or dark color for the encapsulant layer 40. Depending on thedesired application, the encapsulant layer 40 may be configured as clearor light-transmissive, or the encapsulant layer 40 may comprise alight-reflecting or light-redirecting material such as fused silica,fumed silica, or titanium dioxide (TiO₂) particles that form apredominantly white color for the encapsulant layer 40. Other particlesor fillers may be used to enhance mechanical, thermal, optical, orelectrical properties of the encapsulant layer 40. In certainembodiments, the encapsulant layer 40 may include multiple layers withvarying mechanical, thermal, optical, or electrical properties.

After surfaces of the electrical connectors 44 are exposed through theencapsulant layer 40, the plurality of electrically conductive traces42-1 to 42-7 are formed on the encapsulant layer 40 (e.g., on a bottomsurface of the encapsulant layer 40 for the orientation illustrated inFIG. 2D) and certain ones of the electrically conductive traces 42-4 to42-7 are electrically connected to the plurality of LEDs 28-1 to 28-3 byway of exposed surfaces of certain electrical connectors 44. Certainones of the plurality of electrically conductive traces 42-1 to 42-7 maybe configured to provide electrically conductive paths between theplurality of contact pads 38 of the active electrical element 30 and thecathode contacts 34-1 to 34-3 and the anode contacts 36-1 to 36-3 ofeach LED 28-1 to 28-3. As illustrated in FIG. 2C, the electricallyconductive traces 42-1, 42-2, and 42-3 are electrically connected to theactive electrical element 30, but are not electrically connected to anyof the plurality of LEDs 28-1 to 28-3. In this regard, the electricallyconductive traces 42-1, 42-2, and 42-3 may be configured to supplysignals to the active electrical element 30 from an external source(such as the control element 18 of FIG. 1B). Notably, the electricallyconductive trace 42-7 in FIG. 2C is configured to provide anelectrically conductive path between the active electrical element 30and the anode contacts 36-1 to 36-3 of each of the plurality of LEDs28-1 to 28-3. In this regard, the plurality of LEDs 28-1 to 28-3 may beconfigured for common anode control. In other embodiments, the pluralityof electrically conductive traces 42-1 to 42-7 and the plurality of LEDs28-1 to 28-3 may be configured for common cathode control.

FIG. 2E is a bottom view of the LED package 26 of FIG. 2C at asubsequent state of fabrication where an additional encapsulant layer 46and a plurality of package bond pads 48-1 to 48-4 have been formed. FIG.2F is a cross-sectional view taken along the section line C-C of FIG.2E. FIG. 2G is a cross-sectional view taken along the section line D-Dof FIG. 2E where an additional electrical connector 50 is visible.Before formation of the additional encapsulant layer 46 and theplurality of package bond pads 48-1 to 48-4, a plurality of additionalelectrical connectors 50 may be formed on and in electrical connectionwith the electrically conductive traces 42-1, 42-2, 42-3, and 42-7. Theadditional electrical connectors 50 may be configured and formed in asimilar manner to the previously described electrical connectors 44. Incertain embodiments, the additional electrical connectors 50 may beformed on the electrical connectors 44 without an interveningelectrically conductive trace. Alternatively, the additional encapsulantlayer 46 may be applied first and vias or openings for the additionalelectrical connectors 50 may be formed subsequently by a selectiveremoval step such as laser drilling. In a similar manner, a selectiveremoval step may also be used to form openings for the previouslydescribed electrical connectors 44. The additional encapsulant layer 46may then be blanket deposited to cover bottom surfaces of the pluralityof electrically conductive traces 42-1 to 42-7 as well as the additionalelectrical connectors 50. The additional encapsulant layer 46 may beconfigured and formed in a similar manner to the previously describedencapsulant layer 40. Notably, the additional encapsulant layer 46 mayalso be formed on portions of the encapsulant layer 40 that areuncovered by the plurality of electrically conductive traces 42-1 to42-7. In this regard, the encapsulant layer 40 and the additionalencapsulant layer 46 may together form an encapsulant layer 40, 46 thatis continuous such that at least some portions of the plurality ofelectrically conductive traces 42-1 to 42-7 are embedded within theencapsulant layer 40, 46. After formation of the additional encapsulantlayer 46, a removal step (e.g., planarization) as previously describedmay be applied to form exposed surfaces of the plurality of additionalelectrical connectors 50. The plurality of package bond pads 48-1 to48-4 may then be formed on the bottom surface of the additionalencapsulant layer 46 and in electrical communication with the additionalelectrical connectors 50. In this regard, the package bond pads 48-1 to48-4 are configured to receive signals that are external to the LEDpackage 26. In certain embodiments, the package bond pads 48-1 to 48-4are configured to be mounted and bonded to another surface (e.g., amounting surface of an LED panel that includes electrical traces orother types of signal lines) to receive external signals (e.g., from thecontrol element 18 of FIG. 1B). As illustrated, the package bond pad48-4 is electrically connected to the active electrical element 30 by anelectrical path that includes a certain additional electrical connector50 and the electrically conductive trace 42-1. In a similar manner, thepackage bond pad 48-3 is electrically connected to the active electricalelement 30 by a different electrical path that includes a differentadditional electrical connector 50 and the electrically conductive trace42-2. The package bond pad 48-2 is electrically connected to the activeelectrical element 30 by a different electrical path that includes adifferent additional electrical connector 50 and the electricallyconductive trace 42-3. Notably, the package bond pad 48-1 iselectrically connected to the anode contacts 36-1 to 36-3 of each of theLEDs 28-1 to 28-3 by a different additional electrical connector 50 andthe electrically conductive trace 42-7 in a configuration for commonanode control. As previously described, the LED package 26 could beconfigured for common cathode control be rearranging the routing of theplurality of electrically conductive traces 42-1 to 42-7. Additionallayers, such as a solder mask or other insulating layers or materialsmay be applied on selected areas of the additional encapsulant layer 46and the package bond pads 48-1 to 48-4 to further delineate thefootprint of the package bond pads 48-1 to 48-4 and prevent shorting ofsolder material when assembled or mounted on a PCB. In certainembodiments, a plurality of additional encapsulant layers 46 and atleast one additional electrical trace may be formed in a similar mannerbefore the package bond pads 48-1 to 48-4 are formed. In this manner,additional layers of electrical traces may be laminated or alternatingwith the plurality of additional encapsulant layers 46 to provide moreelectrically conductive paths and connections for the LED package 26.

FIG. 2H is a simplified top view of the LED package 26 of FIG. 2E. Inoperation, the view illustrated by FIG. 2H represents a primary emissionface 52 of the LED package 26. The plurality of LEDs 28-1 to 28-3 areaccordingly configured below the submount 32 to provide light emissionsthat pass through submount 32 (e.g., a light-transmissive submount orlight-transmissive superstrate). The active electrical element 30 isalso configured below the submount 32 and all electrical connections andelectrically conductive paths as previously described are accordinglyarranged below the active electrical element 30 and below the pluralityof LEDs 28-1 to 28-3 relative to the primary emission face 52.Accordingly, light generated from the plurality of LEDs 28-1 to 28-3 maypass through the submount 32 and out of the primary emission face 52with reduced losses or absorption to electrical connections,electrically conductive paths, or other elements within the LED package26. In certain embodiments, the plurality of LEDs 28-1 to 28-3 form anLED pixel for the LED package 26 that can be combined with other LEDpackages to form an LED pixel array for video display applications.

FIG. 2I is a simplified bottom view of the LED package 26 of FIG. 2E. Inoperation, the bottom view illustrated by FIG. 2I represents a primarymounting face 54 of the LED package 26. In this regard, the LED package26 is configured to be mounted to an external surface (e.g., a panel orPCB of a video display) such that the package bond pads 48-1 to 48-4 arebonded or soldered to electrical communication lines provided on theexternal surface. In certain embodiments, at least one package bond pad48-1 may comprise an identifier 56, such as a notch, a different shape,or other form of identifier that is configured to convey the polarityand mounting position of the LED package 26 on the external surface.

FIG. 3A is a bottom view of a representative LED package 58 thatincludes a plurality of electrically conductive traces 60-1 to 60-7where portions of the electrically conductive traces 60-1 to 60-4 formpackage bond pads 62-1 to 62-4 for the LED package 58. FIG. 3B is across-sectional view taken along the section line E-E of FIG. 3A. TheLED package 58 may include the submount 32, the encapsulant layer 40,the plurality of LEDs 28-1 to 28-3 with the cathode contacts 34-1 to34-3 and the anode contacts 36-1 to 36-3, and the active electricalelement 30 with contact pads 38 as previously described. Afterplanarizing the encapsulant layer 40 to expose the cathode contacts 34-1to 34-3, the anode contacts 36-1 to 36-3, and the contact pads 38 aspreviously described, the plurality of electrically conductive traces60-1 to 60-7 are formed on the encapsulant layer 40 in a similar mannerto the plurality of electrically conductive traces 42-1 to 42-7 of FIG.2C. As illustrated in FIG. 3A, portions of certain electricallyconductive traces 60-1 to 60-4 are configured with wider areas acrossthe LED package 58. An insulating material 64, such as a solder mask, isthen formed over portions of the electrically conductive traces 60-1 to60-7. Notably, the insulating material 64 does not extend entirely overall of the electrically conductive traces 60-1 to 60-7. In particular,portions of the electrically conductive traces 60-1 to 60-4 areuncovered by the insulating material 64 to form the package bond pads62-1 to 62-4 of the LED package 58. In this regard, the package bondpads 62-1 to 62-4 may be bonded or soldered to another surface and theinsulating material 64 may prevent electrical shorting between differentones of the electrically conductive traces 60-1 to 60-7.

FIG. 4 is a cross-sectional view of an LED package 66 illustratingconfigurations where one or more LEDs 28-1 and the active electricalelement 30 are mounted along a first horizontal plane P₁ of the LEDpackage 66. In FIG. 4 , only the LED 28-1 is illustrated, but it isunderstood the LED package 66 may include a plurality of LEDs that aremounted in a similar manner to the LED 28-1 of FIG. 4 . As illustrated,the LED 28-1 and the active electrical element 30 are mounted or bondedalong the first horizontal plane P₁ that is defined by a mountingsurface of the submount 32. In some embodiments, the LED 28-1 and theactive electrical element 30 may comprise different dimensions, such asdifferent thicknesses or heights relative to the submount 32.Additionally, different thicknesses of bonding layers may be provided torespectively bond the LED 28-1 and the active electrical element 30 tothe submount 32. After bonding the LED 28-1 and the active electricalelement 30 along the first horizontal plane P₁, the electricalconnectors 44, the encapsulant layer 40, the additional electricalconnectors 50, the electrically conductive traces 42-1 to 42-3, theadditional encapsulant layer 46, and the package bond pad 48-1 may beformed as previously described.

FIG. 5 is a cross-sectional view of an LED package 68 illustratingconfigurations where one or more LEDs 28-1 are mounted along the firsthorizontal plane P₁ and the active electrical element 30 is mountedalong a second horizontal plane P₂ that is different than the firsthorizontal plane P₁ of the LED package 68. In FIG. 5 , only the LED 28-1is illustrated, but it is understood the LED package 68 may include aplurality of LEDs that are mounted in a similar manner to the LED 28-1of FIG. 5 . As illustrated, the LED 28-1 is mounted or bonded along thefirst horizontal plane P₁ that is defined by a mounting surface of thesubmount 32. The electrical connectors 44, the encapsulant layer 40, andthe plurality of electrically conductive traces 42-1 to 42-3 are thenformed as previously described. The active electrical element 30 is thenmounted along the second horizontal plane P₂ that is defined by a faceof the plurality of electrically conductive traces 42-1 to 42-3 that isopposite to the LED 28-1. In this manner, the plurality of electricallyconductive traces 42-1 to 42-2 are thereby arranged between the LED 28-1and the active electrical element 30. The additional electricalconnectors 50, the additional encapsulant layer 46, and the package bondpad 48-1 may be subsequently formed as previously described. Notably,the active electrical element 30 may be at least partially embedded inthe additional encapsulant layer 46 in this configuration. Accordingly,the additional encapsulant layer 46 and at least one of the additionalelectrical connectors 50 may comprise greater thicknesses than inpreviously described embodiments. In certain embodiments, the additionalencapsulant layer 46 may comprise a second submount and the activeelectrical element 30 is either embedded within or mounted to the secondsubmount. Such an arrangement may be referred to as a chip-scaleconfiguration.

FIG. 6 is a cross-sectional view of an LED package 70 illustratingconfigurations where one or more LEDs 28-1 and the active electricalelement 30 are mounted to opposing faces of the submount 32. In FIG. 6 ,only the LED 28-1 is illustrated, but it is understood the LED package70 may include a plurality of LEDs that are mounted in a similar mannerto the LED 28-1 of FIG. 6 . As illustrated, the plurality ofelectrically conductive traces 42-1, 42-2 are formed on the second face32″ of the submount 32 and additional electrical traces 71-1, 71-2 areformed on the first face 32′ of the submount 32. The LED 28-1 is mountedor bonded to the electrically conductive traces 42-1, 42-2 by way of theelectrical connectors 44 and the active electrical element 30 is mountedor bonded to the additional electrical traces 71-1, 71-2 by way of theadditional electrical connectors 50. The encapsulant layer 40 is formedover the LED 28-1 and the second face 32″ of the submount 32. In certainembodiments, part of the encapsulant layer 40 forms the primary emissionface 52 of the LED package 70. As previously described, the encapsulantlayer 40 may include a black material to provide improved contrastbetween the LED 28-1 and other LEDs that may be mounted in the LEDpackage 70. In certain embodiments, another layer or an extension of theencapsulant layer 40 may extend above the LED 28-1 to provideencapsulation for the LED 28-1. In such embodiments, the other layer orthe extension of the encapsulant layer 40 above the LED 28-1 maycomprise a light-transmissive materials, additional layers, or textures.The additional encapsulant layer 46 may be formed on the first face 32′of the submount 32 to provide encapsulation for the active electricalelement 30. In this regard, the additional encapsulant layer 46 may ormay not extend across the entire first face 32′ of the submount 32.Notably, portions of the additional electrically conductive trace 71-2that are uncovered by the additional encapsulant layer 46 may form thepackage bond pad 48 as previously described. In order to facilitatebonding to an external surface, a conductive bonding material 72 maycomprise a thickness relative to the submount 32 that is greater than oralmost as thick as the active electrical element 30 and the additionalencapsulant material 46. In order to provide electrical communicationbetween the electrically conductive trace 42-2 and the additionalelectrically conductive trace 71-1, one or more conductive interconnects73, such as metal slugs, vias, or traces may be provided either throughthe submount 32 as illustrated in FIG. 6 , or the conductiveinterconnects 73 may wrap around lateral edges of the submount 32.

FIG. 7 is a bottom view of an LED package 74 that includes a pluralityof LED pixels according to embodiments disclosed herein. The LED package74 is similar to the LED package 26 of FIG. 2E, but includes a pluralityof LED chips 75-1 to 75-3, 76-1 to 76-3, 77-1 to 77-3, and 78-1 to 78-3that respectively form a plurality of LED pixels that are spaced apartfrom one another and packaged together in the same LED package 74. Asillustrated, the LED chips 75-1 to 75-3 form a first LED pixel, the LEDchips 76-1 to 76-3 form a second LED pixel, the LED chips 77-1 to 77-3form a third LED pixel, and the LED chips 78-1 to 78-3 form a fourth LEDpixel. In certain embodiments, each LED pixel comprises a red LED chip,a blue LED chip, and a green LED chip. The LED package 74 furtherincludes an active electrical element 30′ that is configured toelectrically connect with the plurality of pixels, a plurality ofelectrically conductive traces 42-1 to 42-16, and the plurality ofpackage bond pads 48-1 to 48-4 as previously described. Notably, the LEDpackage 74 may be configured with the same number of package bond pads48-1 to 48-4 as previously described for single pixel LED packages(e.g., the LED package 26 of FIG. 2H). As illustrated, the LED package74 comprises four package bond pads 48-1 to 48-4 that are configured forreceiving various combinations of input signals or connections as willbe later described in more detail, such as a supply voltage (V_(dd)), aground (V_(ss)), color select signals, brightness level (or grey level)signals, analog signals, encoded color select signals, encodedbrightness level select signals, digital signals, clock signals, andasynchronous data signals. The active electrical element 30′ therebycomprises four input/output and power connections; however, the activeelectrical element 30′, as will be later described, is configured toindependently alter a driving condition of each LED chip of theplurality of LED chips 75-1 to 75-3, 76-1 to 76-3, 77-1 to 77-3, and78-1 to 78-3. Notably, the electrically conductive trace 42-1 may beelectrically connected to an anode of each of the LED chips 75-1 to75-3, 76-1 to 76-3, 77-1 to 77-3, and 78-1 to 78-3 for common-anodecontrol. The electrically conductive trace 42-1 is also electricallyconnected between the package bond pad 48-1 and the active electricalelement 30′. The electrically conductive trace 42-2 is electricallyconnected between the package bond pad 48-4 and the active electricalelement 30′, the electrically conductive trace 42-9 is electricallyconnected between the package bond pad 48-3 and the active electricalelement 30′, and the electrically conductive trace 42-10 is electricallyconnected between the package bond pad 48-2 and the active electricalelement 30′. In other embodiments, the LED package 74 may be configuredfor common-cathode control as previously described. In order to provideelectrical communication with the increased number of LED pixels withinthe LED package 74, the active electrical element 30′ may comprise anincreased number of the contact pads 38 for communication with anincreased number of the electrically conductive traces 42-1 to 42-16.Four of the contact pads 38 are electrically connected to the packagebond pads 48-1 to 48-4 as previously described, and the remainingcontact pads 38 are electrically connected to different ones of the LEDchips 75-1 to 75-3, 76-1 to 76-3, 77-1 to 77-3 and 78-1 to 78-3. Inorder for the LED package 74 to control multiple LED pixels with areduced number of input signal connections, the active electricalelement 30 may include circuitry configured to receive an inputcommunication signal and perform a subpixel select function toindependently communicate an operating state separately to each of theLED chips 75-1 to 75-3, 76-1 to 76-3, 77-1 to 77-3, and 78-1 to 78-3 ofeach of the LED pixels. In this regard, when a plurality of LED packages74 are arranged together to form an array of LED pixels for a displayapplication, the resulting display will have a reduced number of LEDpackages 74 compared to a similar-sized display where each LED packagecomprises only a single LED pixel. In this regard, a total number ofcommunication signals between an external source (e.g., the controlelement 18 of FIG. 1B) and the LED pixels may be reduced. As with thesingle-pixel embodiments (e.g., FIG. 2E), almost infinite combinationsof routing for communication signals are within the scope of thisdisclosure, including simple variations where one or more metal tracesare configured along the same plane as previously described for FIGS. 3Aand 3B.

FIG. 8 is a block diagram schematic illustrating components of theactive electrical element 30 (or the active electrical element 30′ ofFIG. 7 ) according to embodiments disclosed herein. As previouslydescribed, the active electrical element 30 may be incorporated into anLED package to enable active matrix addressing for a corresponding LEDdisplay. The active electrical element 30 is configured to receive aninput signal from an external source, (e.g., the control element 18 ofFIG. 1B) and independently hold and/or alter a driving condition for oneor more LEDs within the LED package. As will be later described in moredetail, the input signal may comprise a single communication line or aplurality of communication lines in analog, digital, or combinations ofanalog and digital formats. In certain embodiments, the activeelectrical element 30 comprises a memory element 80, which may includeone or more of a volatile and a non-volatile memory element. The memoryelement 80 may comprise one or more of a bipolar transistor, a fieldeffect transistor, an inverter, a logic gate, dynamic random-accessmemory (DRAM), static random-access memory (SRAM), programmableread-only memory (PROM), erasable programmable read-only memory (EPROM),electrically erasable programmable read-only memory (EEPROM), flashmemory, an operational amplifier, a capacitor, and a lookup table, amongothers. In certain embodiments, the memory element 80 comprises at leastone of a sample and hold circuit, a latch circuit, and a flip-flopcircuit. In certain embodiments, the memory element 80 comprises avolatile memory element that is configured to store an operating statefor the one or more LEDs based on the input signal. In operation, eachtime an updated input signal is received by the active electricalelement 30, the volatile memory element is updated with a new operatingstate for the one or more LEDs and the one or more LEDs are accordinglyactivated and held according to the new operating state. In this regard,the volatile memory element may be configured to store a temporaryoperating state and the active electrical element 30 is therebyconfigured to alter a driving condition of the one or more LEDs inaccordance to the temporarily stored operating state. In certainembodiments, the volatile memory element may additionally be configuredto store other states or conditions that may not be consideredtemporary, such as a calibration factor, or an electronic transferfunction such as gain. In this regard, one or more of the temporaryoperating states and the non-temporary states or conditions maycollectively be used to produce driving conditions for the one or moreLEDs. In certain embodiments, the memory element 80 comprises anon-volatile memory element that is configured to store preset data orinformation that may also be used to alter operating states of the oneor more LEDs. The non-volatile memory element, such as a lookup table ora hash table, may be provided to alter the operating states based on anoperating condition or environment of the LED package. For example, athermal management element as shown in FIG. 8 may be incorporated withinthe active electrical element 30 that monitors an operating temperatureof the LED package, and an operating state of the one or more LEDs mayaccordingly be adjusted based on a comparison of the operatingtemperature to a value stored by the non-volatile memory element. Incertain embodiments, the thermal management element comprises atemperature sensor or a temperature sensor input from an externaltemperature sensor. In other embodiments, ambient light levelinformation from a light sensor may be compared to values stored in thenon-volatile memory element to alter a brightness level of the one ormore LEDs. In further embodiments, the non-volatile memory element maybe programmed to store position setting data, including pre-determinedposition setting data or position setting data that is later programmed,for the LEDs or LED pixels of a display. The position setting may beprogrammed before or after installation of an LED display. The positionsetting may include position settings for individual LED chips,individual LED packages that include LED pixels, and individual LEDpanels that may collectively form an LED display. In this regard, commoncontrol lines may be connected to more than one LED, LED pixel, or LEDpackage and the position setting may be used to interpret input signalsand drive only the intended LEDs that are connected by a common controlline.

The active electrical element 30 may additionally comprise one or moreESD protection elements that are configured between the input signal andother components within the active electrical element 30. In certainembodiments, a decoder or control logic element is provided within theactive electrical element 30 to receive and convert one or more of theinput signals into unique combinations of output signals that are inturn used alter different operating states of the one or more LEDs. Inparticular, the decoder or control logic element may output thecombinations of output signals that may be stored and periodicallyupdated in the volatile memory element. Each time the volatile memoryelement is updated, the operating state of the one or more LEDs isaltered or updated via a driver element 82. In certain embodiments, thedecoder element is configured to provide row or column selectinformation for the one or more LEDs or brightness or grey levels foreach of the LEDs. For an LED package configuration that includes aplurality of LED pixels, the decoder element may be configured toprovide pixel or sub-pixel selection within the LED package to thememory element 80. The decoder element may be configured to provideprogramming, set point information, or calibration information to thememory element 80. In certain embodiments, the decoder element may beconfigured to select certain pixels that share a control line bydecoding pre-determined position settings for certain pixels on a sharedcontrol line so only a particular pixel will respond to a controlsignal. The pre-determined position settings may be programmed andstored in the memory element 80, such as the non-volatile memoryelement. In certain embodiments, the driver element 82 (or bufferelement) comprises a source driver element, a sink driver element, orboth a source driver element and a sink driver element. The sourcedriver element is typically used when the LEDs are configured forcommon-cathode control, and the sink driver is typically used when theLEDs are configured for common-anode control. In certain embodiments,the source driver and the sink driver may be included within the activeelectrical element 30 and, accordingly, the source driver and the sinkdriver may be configured to provide a differential voltage output tocontrol the one or more LEDs. In certain embodiments, the activeelectrical element 30 may also include one or more signal conditioningelements that are configured to convert, manipulate, or otherwisetransform control signals before they are received by the source driveror the sink driver. The signal conditioning element may be configured totransform analog signals or digital signals for applications such asgamma correction or apply other nonlinear transfer functions. In certainembodiments, the decoder/control logic directly communicates to thesignal conditioning element, and in other embodiments, thedecoder/control logic assumes the tasks or function of the signalconditioning element in the digital domain. In such embodiments, thesignal conditioning element could simply comprise a wire when thedecoder/control logic assumes the tasks. The signal conditioning elementmay be configured or electrically connected between the memory element80 and the driver element 82 such that a signal leaving the memoryelement 80 may be converted or manipulated before reaching the driverelement 82. The signal conditioning element may be configured orelectrically connected between the input signal and the memory element80 such that the input signal may be converted or manipulated beforereaching the memory element 80. Various other arrangements arecontemplated as the divisions of the various elements of the activeelectrical element 30 can be made in other ways. For example, thedecoder/control logic could be considered as a single processor unitalong with the signal conditioning and memory elements. Additionally,the active electrical element 30 may comprise a plurality of ESDelements, and/or a plurality of decoder/control logic elements, and/or aplurality of memory elements 80, and/or a plurality of signalconditioning elements, and/or a plurality of thermal managementelements, and/or a plurality of driver elements 82 depending on theparticular application. Each of the decoder/control logic elements,memory elements 80, signal conditioning elements, thermal managementelements, and driver elements can be configured as analog elements,digital elements, and combinations of analog and digital elements,including software and firmware and the like.

FIG. 9 is a block diagram schematic illustrating components of theactive electrical element 30 according to embodiments disclosed herein.In FIG. 9 , the active electrical element 30 may include many of thesame components as previously described for FIG. 8 , including the ESDprotection element, the decoder/control logic, the volatile memoryelement, the non-volatile memory element, and the thermal managementelement. As further shown in FIG. 9 , the output of the volatile memoryelement may split into separate signal lines 84-1 to 84-3 for each ofthe LEDs (LED1 to LED3). Each of the separate signal lines 84-1 to 84-3may include a different one of the signal conditioning element, thesource driver element, and the sink driver element as previouslydescribed. In this regard, each of the LEDs (LED1 to LED3) may beindependently driven and altered based on one or more control signalsentering the active electrical element 30. Additionally, in the case ofdifferently colored LEDs, it may be desirable for different LEDs to beconfigured on different power supply lines or supply voltage inputs V₁,V₂. For example, red LEDs typically have a lower turn-on or forwardvoltage (e.g., 1.8-2.4 volts (V)) compared with blue or green LEDs(e.g., 3-3.3 V) due to the lower bandgap of different material systemstypically used to form red LEDs (e.g., GaAs, AlGaInP, GaP-based)compared with blue or green LEDs (e.g., GaN-based). In this regard, theactive control element 30 may be configured with separate connections(e.g., the contact pads 38 of FIG. 2A) that are configured to receive aseparate power supply line or input (e.g., V₁ between about 1.8-2.4 V)for the red LED and a common power supply line or input (e.g., V₂between about 3-3.3 V) for both the blue LED and the green LED.

In addition to various digital memory elements, analog memory elementsmay be used. FIG. 10 is a schematic diagram illustrating an exemplarystructure that includes an analog volatile memory element that may beincluded within active electrical elements according to embodimentsdisclosed herein. In FIG. 10 , an exemplary sample and hold circuit 86is shown that includes a switching device 88, a capacitor 90, anoperational amplifier 92, and an optional operational amplifier buffer94 between an input and the capacitor 90. To sample the input signal,the switching device 88 connects the input signal to the capacitor 90via the operational amplifier buffer 94, and the capacitor 90 stores anelectric charge. After sampling the input signal, the switching device88 disconnects the capacitor 90, and the stored electric charge of thecapacitor 90 discharges through the operational amplifier 92 to providean operational state for a particular LED that is held until the inputsignal is sampled again. In this manner, the optional operationalamplifier buffer 94 and the switching device 88 may be consideredcomponents of the decoder/control logic (FIGS. 8 and 9 ), the capacitor90 may be considered a component of the memory element (FIGS. 8 and 9 ),and the operational amplifier 92 may be considered a component of thesignal conditioning element (FIGS. 8 and 9 ) which may be linear ornon-linear depending on the system configurations.

FIGS. 11A-11F are schematic diagrams illustrating exemplary structuresfor driver elements that may be included within active electricalelements according to embodiments disclosed herein. For video displayapplications, it may be desirable for a driver element to comprise anon-inverting circuit that is configured to drive each LED in a linearmanner from a completely off state of about 0 microamps (μA) or about 0V to about 1 milliamp (mA) or about 3 V with low power consumption. FIG.11A represents an embodiment where a driver element 96 comprises avoltage controlled current source circuit, such as transconductanceamplifier. For a transconductance amplifier, a differential inputvoltage is converted to an output current for driving an LED. In thesimplified schematic of FIG. 11A, the driver element 96 comprises anon-inverting circuit, but the driver element 96 requires connections toboth terminals of the LED for operation leading to a more complex devicelayout. Accordingly, the driver element 96 is not a sinking driverelement for common-anode control or a source driver element forcommon-cathode control. Additionally, a resistor R₁ needs to be large toreduce the input voltage sensitivity, which can reduce the efficiency ofthe driver element 96. Additionally, when the LED is required to turnoff, the output current may have difficulty reaching a low enough value(0 μA) to achieve turn off. FIG. 11B represents an embodiment where adriver element 98 comprises a transconductance amplifier arranged withan active cascode configuration that includes a transistor, such as ametal-oxide-semiconductor field-effect transistor (MOSFET) M₁ and anadditional resistor R₂, which may facilitate complete turn off of theLED. As previously described for FIG. 11A, the voltage sensitivity ofthe driver element 98 can be too high. At full turn on for the LED, orabout 1 mA, the driver element 98 may result in a low voltage input,e.g., about 0.05 V, and, accordingly, the active cascode configurationmay experience an undesirable signal to noise ratio.

FIG. 11C represents an embodiment for a driver element 100 that adds aninput amplifier to the driver element 98 that includes thetransconductance amplifier with the active cascode configuration of FIG.11B. The added input amplifier may serve to de-amplify the voltage forless signal sensitivity and provide improved signal to noise ratio.Additionally, the driver element 100 provides a sinking, or common anodeconfiguration, for the LED; however, the input voltage becomes inverted.FIG. 11D represents an embodiment for a driver element 102 that issimilar to the embodiment of FIG. 11C, but with flipped polarityconnections. In this regard, the driver element 102 includes an inputamplifier between an input voltage and a driver element 98′, which is areversed polarity version of the driver element 98, that includes thetransconductance amplifier with the active cascode configuration of FIG.11B. As illustrated, the driver element 102 represented in FIG. 11Dprovides the advantage of being non-inverting; however, it does resultin sourcing, or common cathode configuration for the LED. Other driverelement arrangements are possible, such as Howland current pumpconfigurations 104, 106 illustrated in FIGS. 11E and 11F. In FIG. 11E,the Howland current pump 104 includes an operational amplifier and aresistor bridge configured to drive the LED. In FIG. 11F, the Howlandcurrent pump 106 additionally includes a voltage divider that includesresistors R₅ and R₆ that is added to the Howland current pump 104 ofFIG. 11E to improve performance when little to no current is flowing.Additionally, an additional operational amplifier is provided at thevoltage input to form a non-inverting voltage follower (e.g., apre-amplifier) to provide high input resistance which is needed for theoutput buffer of the sample and hold circuit to ensure adequate holdtimes.

When a plurality of LED packages as disclosed herein are arranged toform LED pixel arrays for LED display applications, it may beadvantageous if the location of each individual LED package is knownwithin the corresponding active electrical element of each LED packageor that each LED package have a specific address associated with it. Incertain embodiments, each active electrical element within each LEDpackage is configured to store location or address specific information,such as the particular row and column in which the LED package isregistered. In this regard, display control units may send signalsacross the LED pixel array that are encoded for specific locationswithin the LED pixel array, and each active electrical element of eachindividual LED package is thereby configured to interpret the signalsand determine whether to respond or ignore a certain signal based on thelocation or address information. In certain embodiments, the activeelectrical element of each LED package comprises a detector element thatis configured to detect the location of the LED package within an arrayof LED packages in a display and working in conjunction with a mastercontroller (e.g., the control element 18 of FIG. 1B along with otherhardware/software configurations), relay that information for memorystorage within the active electrical element. This task may be performedafter PCB assembly when a special configuration program is run toproperly set and store the address and calibration information intonon-volatile memory of the active electrical element, in one or moreremote memory devices, or in both the active electrical element and oneor more remote memory devices.

FIG. 12A is a block diagram schematic illustrating an embodiment of theactive electrical element 30 that includes a detector/signal conditionalelement. As previously described, the active electrical element 30 maybe incorporated into an LED package to enable an LED display that isconfigured for active matrix addressing. The active electrical element30 is configured to receive an input signal from an external source,(e.g., the control element 18 of FIG. 1B) and independently alter adriving condition for one or more LEDs within the LED package. The blockdiagram of FIG. 12A is similar to the block diagram of FIG. 8 andincludes the memory element 80 and the driver element 82 as previouslydescribed. As illustrated, the ESD protection element, thedecoder/control logic element, the thermal management element, and thesignal conditioning element may also be included as previouslydescribed. In certain embodiments, one or more of the LEDs may be usedas a light detector to generate a signal that is received by thedetector/signal conditioning element. For example, after installation ofa plurality of LED packages in an LED pixel array, all LED packages thatare connected to a common data bus may lack individual unique addresses.In this regard, an initial setup procedure (or location setup procedure)may be performed where each of the LED packages may be scanned with alight beam and at least one LED within each of the LED packages mayserve as a photodiode that provides a corresponding voltage and/orcurrent signal that corresponds with the particular location of the LEDpackage. In this manner at least one of the LEDs may operate in aphotovoltaic or photoconductive mode during the initial setup procedure.The signal produced by the light beam is used in conjunction withelectrical signals from the master controller (e.g., the control element18 of FIG. 1B along with other hardware/software configurations)provided over the data bus to cause the component to record its address.When encoded signals for each pixel location are sent across the LEDpixel array, each LED package may therefore be configured to know whichsignal the LED package is supposed to respond to. For such embodiments,the LED driver element 82 may be configured with a high impedance outputto support a light detector mode of the one or more LEDs during theinitial setup procedure. In certain embodiments, the detector/signalconditioning element may comprise a voltage detector, a current sensor,or even a wire that delivers the location signal to the decoder/controllogic element. In this manner, the active electrical element 30 may beconfigured to be addressed and an operating state of the at least one ofthe LEDs may be altered in a way dependent on information such as anaddress stored in local memory. In certain embodiments, a separatephotodiode that is not one of the LEDs within the LED package may beconfigured within the LED package to provide the location signal to theactive electrical element 30. In certain embodiments, thedetector/signal conditioning element may be configured to monitoroperation voltages or currents of the LEDs and store such information inthe memory element. In this regard, the active electrical element 30 isconfigured to store monitoring information that includes operatingtemperature from the thermal management element, positional information,or voltage or current information from the LEDs via the detector/signalconditioning element. In certain embodiments, the active electricalelement 30 may be configured to communicate such monitoring informationwith an external source (e.g., the control element 18 of FIG. 1B or aseparate device) so that the LED display may be configured toself-monitor various operating conditions and generate reports or visualindications if any of the monitored operating conditions are outside oftarget windows. In this regard, the active electrical element 30 may beconfigured for bi-directional communication with the external source.

FIG. 12B is a bottom view of an LED package 108 that includes aphotodiode 110 according to embodiments disclosed herein. The LEDpackage 108 is similar to the LED package 74 of FIG. 7 , and includesthe plurality of LED chips 75-1 to 75-3, 76-1 to 76-3, 77-1 to 77-3, and78-1 to 78-3 that respectively form a plurality of LED pixels and theactive electrical element 30′ as previously described. The LED package108 may also include the package bond pads 48-1 to 48-4 and theelectrically conductive traces (42-1 to 42-16 of FIG. 7 ). Asillustrated, the LED package 108 comprises the photodiode 110 that isconfigured to detect and communicate a light signal to other componentsof the active electrical element 30′ as described in FIG. 12A. Incertain embodiments, the active electrical element 30′ comprises thephotodiode 110. In certain embodiments, the photodiode 110 is arrangedon the active electrical element 30. In other embodiments, thephotodiode 110 is arranged outside of the active electrical element 30′.For example, in certain embodiments, the LED package 108 includes blackencapsulant materials that cover the LED package 108 except for areasregistered with each of the LED chips 75-1 to 75-3, 76-1 to 76-3, 77-1to 77-3, and 78-1 to 78-3. In this regard, the photodiode 110 may bearranged adjacent to one of the LED chips 75-1 to 75-3, 76-1 to 76-3,77-1 to 77-3, and 78-1 to 78-3 such that an adequate amount of a lightsignal may reach the photodiode 110 without being absorbed by the blackencapsulant materials. In other embodiments, the photodiode may beincorporated within other LED packages, including the LED package 26 ofFIG. 2H, the LED package 58 of FIG. 3A, the LED package 66 of FIG. 4 ,the LED package 68 of FIG. 5 , and the LED package 70 of FIG. 6 , amongothers. As previously described, the photodiode 110 may be omitted incertain embodiments and one or more of the LED chips 75-1 to 75-3, 76-1to 76-3, 77-1 to 77-3, and 78-1 to 78-3 may serve as a photodiode whenscanned with a light beam during an initial setup procedure.

FIG. 13 is block diagram schematic illustrating various components thatmay be included in a system level control scheme for an LED displaypanel according to embodiments disclosed herein. In certain embodiments,the components of the system level control scheme may be included on abackside of a display panel as previously illustrated in FIG. 1B. Inoperation, input signals are received by the LED display panel from anexternal video source. As previously described, a video source such as aVGA, DVI, HDMI, HUB75, USB, among others, is provided through anappropriate electrical connector. A signal decoder, such as a DVI/HDMIdecoder may be configured to provide conversion of the input signals toother formats, such as 24-bit transistor-to-transistor logic (TTL) orcomplementary metal-oxide-semiconductor (CMOS) color pixel data. Forexample, the signal decoder may convert the input signal into a 24-linedata bus along with other control signals, such as the pixel clock,vertical sync, and horizontal sync that is then routed to the controlelement. As previously described, the control element may comprise oneor more of an ASIC, a microcontroller, a programmable control element,and a field-programmable gate array FPGA. For example, the controlelement may comprise a FPGA that is programmed to scale, offset, orotherwise transform the converted data from the signal decoder andprovide buffering of the data for control lines that will ultimatelydeliver various signals to the LED packages and corresponding LED pixelsof the LED display panel. In certain embodiments, the control element isalso configured to receive additional inputs that are used to transformthe input signals. For example, the additional inputs may includehorizontal and vertical panel position information of the LED displaypanel within a larger LED display. When multiple LED display panels areassembled together to form the larger LED display, each of the LEDdisplay panels may be configured with a unique position identifier thatis relayed to the control element. The unique identifier, such as aserial number or position coordinates, may be pre-assigned before orduring installation or the unique identifier may be assigned simply bythe order of which they are connected when the LED display panels areassembled. In the latter configuration, each of the LED display panelsmay be configured to communicate with each other via shift registers orthe like such that during installation, as the LED display panels arearranged next to each other in a daisy chain configuration, positioninformation is relayed to from one LED display panel to the next LEDdisplay panel in the order they are installed, in a similar manner toHUB75 compatible panels. The additional inputs may also include acalibration table, such as a hash table, that provides information sothat the control element may transform the input signals in a mannerthat compensates for any uneven performance characteristics between LEDchips of the LED display panel. For example, after assembly of the LEDdisplay panel, the intensity of every LED pixel may be measured and thecalibration table may then be configured to provide information to thecontrol element to scale drive signals differently to different LEDpixels based on their initial measured brightness levels.

The control element may thereby be configured to receive input signalsvia the signal decoder as well as additional inputs including panelposition or calibration information. As previously described, thecontrol element may comprise one or more integrated circuits of varioustypes. In certain embodiments, the control element comprises an ASICthat is pre-configured for application in the LED display panel. Inother embodiments, the control element comprises an FPGA that providesthe ability to be programmed and reprogrammed after installation. Assuch, other supporting devices such as power input and conditioners, aprogramming interface, volatile and non-volatile memory elements and thelike are implied. The control element is configured to process the inputsignals as well as any of the additional inputs and output controlsignals that are sent to the active electrical elements of each of theLED pixels. In certain embodiments, a plurality of DACs may be arrangedto convert signals from the control element before routing the signalsto the LED pixels. The control element may also be configured to outputcolumn, row, and LED color select information to the LED pixels thatdetermines when each LED pixel and each LED chip within each LED pixelresponds to the control signals from the plurality of DACs. In certainembodiments, one or more column, row, or color select decoders may beconfigured to receive and transform the output column, row, and/or LEDcolor select information from the control element before routing to theLED pixels. For example, the control element may comprise an FPGA thatoutputs a digital signal code of 0's and 1's for the column, row, orcolor select information. In turn, the column, row, or color selectdecoders may be configured to receive and decode the digital signal sothat the active control element of a particular LED pixel within the LEDdisplay panel may be activated.

For display applications, an LED display panel may include a pluralityof LED packages arranged in columns and rows to form an LED pixel array.Each of the LED packages may include one or more LED pixels that includea first LED chip (e.g., a red LED chip), a second LED chip (e.g., a blueLED chip), and third LED chip (e.g., a green LED chip) and an activeelectrical element as previously described. Depending on the drivingconfiguration between the control element and the LED packages, thenumber of control lines and the number of row, column, color selectlines that are connected between the control element and each LEDpackage may be varied.

FIG. 14 is a schematic illustration representing a configuration wherethe active electrical element 30 corresponding to a particular LED pixelis configured to receive a row select signal line as well as separatecontrol signals for each of the red, green, and blue LED chips that areincluded within the LED pixel. In this regard, the row select signalactivates each active electrical element 30 of a particular row of LEDpixels, and each column of LED pixels is configured to receive the threeseparate control signals for each of the red, green and blue LED chips.The three separate control signals may correspond to three separate DACsper column, or analog control signals. The control signals may control abrightness level, or grey level, for each of the red, green and blue LEDchips within a particular LED pixel. Accordingly, when the controlsignals are passed along a particular column, the row select signaldetermines which of the LED pixels responds to the signal. As previouslydescribed, the active electrical element 30 corresponding to each LEDpixel is configured to store the red, green, and blue level signalinformation and accordingly drive the LED chips in a constant manneruntil the next time the active electrical element 30 is activated torefresh or update the signal information. Accordingly, for theconfiguration of FIG. 14 , the active electrical element 30 isconfigured with connections to receive four different signal lines (RowSelect, Red Level, Green Level, Blue Level) in addition to ground andvoltage input connections. Accordingly, this configuration requires atleast six connections with increased PCB routing complexity. In certainembodiments, it may be desirable to have fewer connections, such as the4-connection embodiments shown in previous embodiments (e.g., FIG. 2E).

FIG. 15 is a schematic illustration representing a configuration wherethe active electrical element 30 corresponding with a particular LEDpixel is configured to receive a separate row select signal line foreach LED chip of the LED pixel and a single color level signal line forall of the LED chips within the LED pixel. In FIG. 15 , three separaterow select signals (Red Row Select, Green Row Select, Blue Row Select)are to separately activate each of the red, green, and blue LED chipswithin the LED pixel. Accordingly, a single color level (e.g.,brightness level or grey level) may be provided for each of the red,green, and blue LED chips within the LED pixel. In this regard, eachcolumn may be configured with a single DAC as previously described. Inother embodiments, the active electrical element 30 may be configured toreceive an optional column select line, thereby allowing a single DAC toprovide color level signals for multiple columns of LED pixels. Inoperation, a particular row select signal activates a particular LEDchip for responding to the color level signal at a particular time. Aswith previous embodiments, the active electrical element 30 isconfigured to store the color level signal information and accordinglydrive each of the LED chips until the next time the active electricalelement 30 is activated to refresh or update the color levelinformation. Accordingly, for the configuration of FIG. 15 , the activeelectrical element 30 is configured with connections to receive four tofive different signal lines (Red Row Select, Blue Row Select, Green RowSelect, Color Level, and optional Column Select) in addition to groundand voltage input connections. Although the overall system complexity isreduced by the reduction of DACs, the requirement of at least sixconnections may be undesirable for some applications.

FIG. 16 is a schematic illustration representing a configuration wherethe active electrical element 30 corresponding with a particular LEDpixel is configured to receive encoded row select signals for each LEDchip of the LED pixel and a single color level signal line for all ofthe LED chips within the LED pixel. In FIG. 16 , the color level andoptional column select lines may be configured the same as previouslydescribed for FIG. 15 ; however, the row select signals are reduced totwo row select lines (Row Select RS0, Row Select RS1). In this regard,the row select lines are configured to provide an encoded digital signal(combinations of 0's and 1's) that determine which LED chip shouldrespond to a particular color level signal. By way of a non-limitingexample, the two row select lines could provide a “00” digital signalcorresponding to an operating state where none of the LED chips shouldrespond, a “01” digital signal corresponding to activation of the redLED chip, a “10” signal corresponding to activation of the blue LEDchip, and a “11” signal corresponding to activation of the green LEDchip. As with previous embodiments, the active electrical element 30 isconfigured to store the color level signal information and accordinglydrive each of the LED chips in a constant manner until the next time theactive electrical element 30 is activated to refresh or update the colorlevel information. Accordingly, for the configuration of FIG. 16 , theactive electrical element 30 is configured with connections to receivethree to four different signal lines (Row Select RS0, Row Select RS1,Color Level, and optional Column Select) in addition to ground andvoltage input connections. Accordingly, the reduction of at least oneconnection represents an improvement in reduced PCB complexity comparedwith the embodiments of FIGS. 14 and 15 .

FIG. 17 is a schematic illustration representing a configuration wherethe active electrical element 30 of a particular LED pixel is configuredto receive a row select signal, a color level signal, and one or morecolor select signals for the red, green, and blue LED chips that areincluded within the LED pixel. In FIG. 17 , the row select signal isconfigured the same as the configuration of FIG. 14 ; however, thesignal for color level (e.g., the brightness or grey level) of each ofthe LED chips is controlled by a single signal line. In this regard,each column may be configured with a single DAC as previously described.In other embodiments, a single DAC may be configured to provide signalsfor color level to multiple columns of LED pixels. In order to determinewhich of the LED chips within the LED pixel should respond to aparticular color level signal, two color select lines (Color Select 0,Color Select 1) are configured to provide an encoded digital signal(combinations of 0's and 1's) that determine which LED chip shouldrespond to a particular color level signal. By way of a non-limitingexample, the two color select lines could provide a “00” digital signalcorresponding to an operating state where none of the LED chips shouldrespond, a “01” digital signal corresponding to activation of the redLED chip, a “10” signal corresponding to activation of the blue LEDchip, and a “11” signal corresponding to activation of the green LEDchip. Accordingly, for the configuration of FIG. 17 , the activeelectrical element 30 is configured with connections to receive fourdifferent signal lines (Row Select, Color Level, Color Select 0, ColorSelect 1) in addition to ground and voltage input connections.

FIG. 18 is a schematic illustration representing a configuration similarto both the configurations of FIG. 16 and FIG. 17 . In particular, FIG.18 represents a configuration independent notation that could representeither of the configurations of FIG. 16 or FIG. 17 . In FIG. 18 , theactive electrical element 30 includes a color level line which is thesame as the color level lines in FIG. 16 and FIG. 17 . The activeelectrical element 30 of FIG. 18 additionally includes a device select(DS) line and two color select lines (CS0 and CS1). The DS line isconfigured to provide a device select signal that may include at leastone of a row select signal and a column select signal. The CS0 and CS1lines are configured to provide encoded signals that could correspond toeither the Row Select RS0 and Row Select RS1 lines of FIG. 16 or theColor Select 0 and Color Select 1 lines of FIG. 17 . In this regard, theactive electrical element 30 may be configured to control a certainnumber of operating conditions with a few number of connections. The DSline corresponds with either the Column Select line of FIG. 16 or theRow Select line of FIG. 17 .

FIG. 19 is a schematic illustration representing a configuration wherethe active electrical element 30 corresponding with a particular LEDpixel is configured to receive a single row select signal line and asingle color level signal line for all LED chips of the LED pixel. InFIG. 19 , the color level and optional column select lines may beconfigured the same as previously described for FIG. 15 ; however, therow select signals are combined into a signal row select line. In thisregard, the single row select line may be configured to send an encodedsignal that separately corresponds to each of the LED chips within theLED pixel. The encoded signal may comprise an analog signal thatcomprises at least one of a variable amplitude signal, a variablefrequency signal, or a variable phase signal. The encoded signal mayalso comprise a multiplexed or multiple level logic signal. In certainembodiments, the row select line may be configured to provide a signalwith different voltage states that correspond to different ones of theLED chips. For example, the row select line may be configured as afour-level signal line where each of the four signal levels correspondsto one of the following operational conditions: no LED chips selected,red LED select, blue LED select, and green LED select. In certainembodiments, an additional active electrical element may be provided tofurther facilitate processing of the four-level signal line. Theadditional active electrical element may be provided within each LEDpackage or separately from each LED package. As with previousembodiments, the active electrical element 30 is configured to store thecolor level signal information and accordingly drive each of the LEDchips in a constant manner until the next time the active electricalelement 30 is activated to refresh or update the color levelinformation. Accordingly, for the configuration of FIG. 19 , the activeelectrical element 30 is configured with connections to receive two tothree different signal lines (Row Select (multi-Level), Color Level, andoptional Column Select) in addition to ground and voltage inputconnections. This configuration is desirable for applications withreduced-complexity, such as the 4-connection configurations previouslydescribed (e.g., FIG. 2E).

FIG. 20 is a schematic illustration representing a configuration wherethe active electrical element 30 corresponding with a particular LEDpixel is configured to receive a single row select signal line and asingle color level signal line for all LED chips of the LED pixel. FIG.20 is similar to the configuration of FIG. 19 and includes the colorlevel and optional column select lines as previously described. In FIG.20 , the row select signal line may be configured to send an encodedsignal, such as an encoded digital signal that is asynchronous, portionsof which separately correspond to each of the LED chips within the LEDpixel. In certain embodiments, the encoded signal comprises differentpulses that correspond to each of the red LED select, blue LED select,green LED select, and no LED select operational conditions. Otheroperational states may be addressed as well by extending the codingschemes. In this manner, the active electrical element 30 may comprise ashift register that cycles through each of the operational states (e.g.,no select, red select, blue select, green select) sequentially with eachpulse of the encoded signal. In order to prevent the shift register fromgetting out of sync, the encoded signal may also comprise a pulse codeat the end of each cycle to reset the shift register to the beginning ofthe next cycle. In addition to sequential pulses, the row select linemay comprise other encoded signals that identify and correspond todifferent ones of the four or more operational states mentioned above.Accordingly, for the configuration of FIG. 20 , the active electricalelement 30 is configured with connections (e.g., the contact pads 38 ofFIG. 2A) to receive two to three different signal lines (Row Select(encoded), Color Level, and optional Column Select) in addition toground and voltage input connections. As with the configuration of FIG.19 , the configuration of FIG. 20 is desirable for applications withreduced-complexity, such as the 4-connection configurations previouslydescribed (e.g., FIG. 2E).

FIG. 21 is a block diagram schematic illustrating a system level controlscheme for an LED display panel where each active electrical element ofan LED pixel array is configured to receive signal lines according tothe embodiment of FIG. 20 . In FIG. 21 , input signals, the signaldecoder, the control element, the row/column decoder, the panel positioninput, the calibration table input, and the plurality of DACs may beprovided as previously described for FIG. 13 . In FIG. 21 , no columnselect lines are included and an optional DAC decoder element isarranged to allow selection of the proper DAC element to receive dataprovided by a common data bus. In other embodiments, the control elementmay be configured to include DAC decoding capabilities and, accordingly,the DAC decoder element may not be required. Depending on the number ofoutput pins available on a particular FPGA or other control element, aseparate row/color decoder may also not be required.

FIG. 22 is a partial plan view illustrating a routing configuration foran LED panel 112 that is configured for operation according to theconfiguration of FIG. 20 and FIG. 21 . In FIG. 22 , a plurality of LEDpackages 26 are arranged in rows and columns to form an LED pixel array.Each LED package 26 may include the plurality of LEDs (e.g., 28-1 to28-3 of FIG. 2 ) that form an LED pixel, the active electrical element(30 of FIG. 2 ), and the plurality of package bond pads 48-1 to 48-4 aspreviously described. As illustrated in FIG. 22 , the plurality of LEDpackages 26 are connected to a plurality of color level control lines114-1 to 114-4 that correspond to the color level select line of FIG. 20and a plurality of row select control lines 116-1 to 116-3 thatcorrespond to the row select line of FIG. 20 . For the LED package 26that is labeled in FIG. 22 , the package bond pad 48-1 is connected tothe color level control line 114-1, and the package bond pad 48-3 isconnected to the row select control line 116-3. The package bond pad48-2 is connected to a voltage input line 118-1 of a plurality ofvoltage input lines 118-1 to 118-4 and the package bond pad 48-4 isconnected to a ground connection plane (not shown). In certainembodiments, the plurality of color level control lines 114-1 to 114-4and the plurality of row select control lines 116-1 to 116-3 may bearranged on different levels or planes of a multiple-layer connectorinterface with one or more dielectric layers arranged therebetween forelectrical insulation. For example, the row select control lines 116-1to 116-3 may be arranged along a first plane that is closest to theplurality of LED packages 26. The plurality of color level control lines114-1 to 114-4 and the plurality of voltage input lines 118-1 to 118-4may be arranged along a different plane at a greater distance away fromthe plurality of LED packages 26. Finally, a ground connection plane(not shown) may be arranged along another different plane at a greaterdistance away from the plurality of LED packages 26 than the pluralityof color level control lines 114-1 to 114-4 and the plurality of voltageinput lines 118-1 to 118-4. A plurality of vias 120 may be arrangedthrough the multiple-layer connector interface to provide correspondingconnections with the package bond pads 48-1 to 48-4. FIG. 22 illustratesonly one of many configurations for a routing configuration of the LEDpanel 112. In other embodiments, the various lines 114-1 to 114-4, 116-1to 116-3, and 118-1 to 118-4 may be provided in different arrangementsof vertical and horizontal configurations, including but not limited to,all vertical and all horizontal configurations.

FIG. 23 is a schematic illustration representing a configuration wherethe active electrical element 30 corresponding with a particular LEDpixel is configured to receive all-digital communication for row,column, and/or color select signals. In addition, two-way communicationmay be achieved by one of many standard or custom protocols. As such,many additional tasks are enabled such as communication handshaking,addressing, status reporting, and a more extensive command structure.Stated differently, the active electrical element comprises a serialcommunication element. In this manner, a serial input/output line isconfigured to provide digital signals to the active electrical element30 according to one of various serial communication link techniques.Serial communication techniques typically involve sending or streamingdata in single bits sequentially over time. An optional clock input maybe configured to receive a clock signal that provides cyclinginformation for the LED pixel. In certain embodiments, serialcommunication (e.g., sending or receiving) may comprise high bit rateswith differential signaling, including but not limited to low voltagedifferential signaling (LVDS), transition-minimized differentialsignaling (TDMS), current mode logic (CML), and source-coupled logic(SCL). In this regard, the active electrical element 30 may beconfigured to receive an optional differential input/output line and anoptional clock differential input/output line. Certain serialcommunication techniques may be configured with self-clockingconfigurations or configurations for receiving self-clocking signals,and, accordingly, the clock input may not be required. Suchself-clocking configurations may comprise a decoder element within theactive electrical element that includes various decoding capabilitiesfor clock recovery, such as 8b/10b encoding, Manchester coding, phasecoding, pulse counting with or without a timed reset, isochronous signalcoding, or anisochronous signal coding. Other communication techniquesmay include inter-integrated circuit (I²C) protocol, I3C protocol,serial peripheral interface (SPI), ethernet, Fibre Channel (FC),universal serial bus (USB), IEEE 1394 or FireWire, HyperTransport (HT),InfiniBand (IB), digital multiplex (DMX), DC-BUS or other power linecommunication protocols, avionics digital video bus (ADVB), serialinput/output (S10), controller area network (CAN), ccTalk protocol,CoaXPress (CXP), musical instrument digital interface (MIDI),MIL-STD-1553, peripheral component interconnect express (PCI Express),profibus, RS-232, RS-422, RS-423, RS-485, serial digital interface(SDI), serial AT attachment (Serial ATA), serial attached SCSI (SAS),synchronous optical networking (SONET), synchronous digital hierarchy(SDH), SpaceWire, UNI/O bus, and 1-Wire, among others. For someconfigurations, the active control element 30 is configured to operate(e.g., send or receive) with at least a subset of signals that arecompatible with one of the above protocols, including but not limited tothe I²C protocol. When arranged for all-digital communication, theactive electrical element 30 is configured to latch input data,implement other logic, and provide the color level, or grey level, toLED pixels of a display. In certain embodiments, the active electricalelement 30 may comprise a DAC-controlled current driver where one ormore DACs are included within the active electrical element 30 withcurrent driving output. In certain embodiments, the active electricalelement 30 comprises a PWM driver or current source that is configuredto independently drive each LED of an LED pixel based on digital inputsignals. When the active electrical element 30 is arranged for alldigital communication, routing for an LED pixel array may be simplified.In this regard, each active electrical element 30 may only need to beconfigured to receive as little as one communication or signal line,such as the serial input/output line illustrated in FIG. 23 , in certainembodiments.

FIG. 24 is a block diagram schematic illustrating a system level controlscheme for an LED display panel where each active electrical element ofan LED pixel array is configured to receive signal lines according tothe embodiment of FIG. 23 . In FIG. 24 , input signals, the signaldecoder, the panel position input, and the calibration table input maybe provided as previously described for FIG. 13 . In certainembodiments, the control element comprises one or more a serialcommunication interfaces or serial communication elements as previouslydescribed. Accordingly, no DAC elements are needed, thereby providing asimplified configuration compared with the block diagram of FIG. 21 .Depending on the number of output pins available on a particular FPGA orother control element, a separate row/color decoder may also not berequired. As illustrated, the output of the control element maycommunicate directly to the LED array with a plurality of serial outputsin communication with a plurality of serial lines or strings of LEDs ofthe LED array. In FIG. 24 , each string of LEDs is shown with twocolumns for illustrative purposes. In practice, the strings of LEDs maybe arranged in rows and columns of different sizes and numbers, or theelectrical connections for each string may not follow the rows andcolumns as shown.

FIG. 25 is a partial plan view illustrating a routing configuration foran LED panel that is configured for operation according to theconfiguration of FIG. 23 . In FIG. 25 , a plurality of LED packages 26are arranged in rows and columns to form an LED pixel array. Each LEDpackage 26 may include the plurality of LEDs (e.g., 28-1 to 28-3 of FIG.2 ) that form an LED pixel, the active electrical element (e.g., 30 ofFIG. 2 ), and the plurality of package bond pads 48-1 to 48-4 aspreviously described. In this configuration, the control lines 116-1 to116-4 correspond to the serial input/output line of FIG. 23 , the firstand second voltage input lines 118-1 to 118-4 and 120-1 to 120-4, andthe ground connection lines 122-1 to 122-4 illustrated. As illustrated,no color level control lines from DACs (e.g., 114-1 to 114-4 of FIG. 22) are required, thereby providing a simplified PCB routingconfiguration. In FIG. 25 input electrical connections that include thecontrol lines 116-1 to 116-4, the voltage lines 118-1 to 118-4, 120-1 to120-4, and the ground lines 122-1 to 122-4 are all arranged along thesame plane or layer of the LED panel. This configuration provides a moresimple structure and fabrication process, as well as reduced costs. Inother embodiments, the control lines 116-1 to 116-4, voltage lines 118-1to 118-4, 120-1 to 120-4, and the ground lines 122-1 to 122-4 may beconfigured on different planes with different arrangements of dielectriclayers and vias to make the various connections to each LED package 26.In FIG. 25 , the control lines 116-1 to 116-4, voltage lines 118-1 to118-4, 120-1 to 120-4, and the ground lines 122-1 to 122-4 areillustrated with long linear segments across the LED panel. In certainembodiments, the control lines 116-1 to 116-4, voltage lines 118-1 to118-4, 120-1 to 120-4, and the ground lines 122-1 to 122-4 may bearranged in other configurations, such as comb routing or other chainconfigurations that may reduce crosstalk between various lines. Incertain embodiments, the control lines 116-1 to 116-4, voltage lines118-1 to 118-4, 120-1 to 120-4, and the ground lines 122-1 to 122-4 maynot be registered with particular rows and columns of LED packages 26.For example, the control lines 116-1 to 116-4, voltage lines 118-1 to118-4, 120-1 to 120-4, and the ground lines 122-1 to 122-4 may beconfigured to connect and communicate with subgroups of the LED packages26 that are arranged in blocks or other shapes across the LED panel.

In certain embodiments, signal communication between a control elementand LED packages of an LED display may comprise sending a control signalfrom the control element that includes a plurality of data packets. Aparticular data packet may include control information such as colorselect data and brightness level data for an individual LED package ofan array. In certain embodiments, a data packet may comprise a file sizethat includes a range including as low as a single bit of data to muchlarger file sizes (e.g., large video files). Each data packet may alsoinclude a command code that is configured as an identifier or a seriesof identifiers that enables each LED package of the array to receive thecommand code and either respond to the data packet or pass the datapacket along to the next LED package. In this manner, the LED packagesmay be arranged to receive different data packets from the controlsignal in a cascading manner.

FIGS. 26A and 26B are schematic diagrams illustrating arrangements of anexemplary data packet 124 according to embodiments disclosed herein. Thedata packet 124 is included in a data stream 126 that is sent via acontrol line from the control element 18 to the active electricalelement 30 of the LED package 26. In certain embodiments, the datastream 126 may include a plurality of data streams, including a cascadeapproach where the data stream 126 comprises a plurality of sub-datastreams. In certain embodiments, the LED package 26 forms one or morepixels (e.g., 12 of FIG. 1A) as previously described. There may beadditional LED packages arranged before or after the LED package 26 thatare configured to receive the data stream 126. In this manner, the LEDpackage 26 may receive the data packet 124 directly from the controlelement 18 or through another LED package that is arranged in the datastream 126 and between the control element 18 and the LED package 26.The data packet 124 may include an information or data section(indicated as “Data”) for selecting and operating one or more LED chipsof the LED package 26, including separate color select and brightnesslevel data for each LED chip that is arranged within the LED package 26.The information or data may also include setup data, calibration data,temperature compensation data, and option select data, among others.Additionally, the data packet 124 may include instructions for turningon or off one or more LED chips of the LED package 26. In certainembodiments, at least some of the information or data from the datapacket 124 may be stored in a register within the LED package 26 forlater use. For applications where the LED package 26 forms one or moreLED pixels that include multiple LED chips (e.g., red, green, and blueLED chips), the information or data may comprise data subsets thatcorrespond to individual ones of the LED chips. The data packet 124 mayalso include a section that comprises a command code (indicated as“Command”) that is configured as an identifier or a series ofidentifiers for the data packet 124 that identifies how the activeelectrical element 30 should respond to the data packet 124. Inparticular, the command code is configured to identify an action for theactive electrical element 30 to take. In certain embodiments, the actioncomprises passing the data packet 124 through the LED package 26, ortransmitting or retransmitting the data packet 124 through an outputport of the LED package 26. In certain embodiments, the action comprisesperforming an internal action within the LED package 26 such as drivingone or more of the LED chips within the LED package 26 and transmittingthe data packet 124 through the LED package 26. As used herein, aninternal action to the LED package 26 may include setting up or changingof a persistent state for a time frame defined by the data packet 124 orany other associated data packets for the given time frame. Thepersistent state may include one or more of turning one or more LEDchips on or off, changing color or brightness levels of the LED chips,or setting up or updating calibration data, among others. In certainembodiments, the action comprises driving one or more of the LED chipswithin the LED package 26 without transmitting the data packet 124through the LED package 26. In certain embodiments, the action comprisestransmitting the data packet 124 without performing any other actionsinternal to the LED package 26. Such actions may at least be partiallybased one or more other data packets previously received by the LEDpackage 26. In further embodiments, another data packet, or a seconddata packet, that is received by the LED package 26 may comprise asecond command code that identifies a second action to take, the secondaction comprising transmitting the second data packet through the LEDpackage 26. In other embodiments, the second action comprises drivingone or more of the LED chips within the LED package 26 and transmittingthe second data packet through the LED package 26. In this manner, thedata packet 124 is configured with self-identification. In certainembodiments, the data packet 124 may comprise information that isconfigured to provide data handshaking with another LED package in thedata stream 126. Data handshaking capabilities may include a beginningof packet section (indicated as “BOP”) and/or an end of packet section(indicated as “EOP”) of the data packet 124 such that the LED package 26can acknowledge receipt and/or transfer of the data packet 124. Incertain embodiments, the data steam 126 may comprise an empty spacesection (indicated as “Space”) that is a period of no data or an emptytransmission period that is arranged before or after the data packet 124in the data stream 126. The period of no data transmission may beconfigured to control communication speed and prevent buffer overrun ofthe control signal for the LED package 26. For example, if multiple LEDpackages 26 with different communication speeds or clockingconfigurations are arranged to receive different data packets from thedata stream 126 in a cascading manner, data overrun can occur.Accordingly, the period of no data transmission may be provided toensure communication effectively runs at a controlled or slower speedsto avoid or reduce buffer overrun. The period of no data transmissionmay also be configured to signal a reset or restart condition, or signala next frame condition. The period of no data transmission may beconfigured at different locations relative to the data packet 124, suchas after the data packet 124 as illustrated in FIG. 26A, or before thedata packet 124 as illustrated in FIG. 26B. In certain embodiments, thedata packet 124 may include other commands, such as basic on or offinstruction for the corresponding LED package 26.

FIG. 27 is a schematic diagram illustrating a cascading flow of aplurality of data packets DP₁, DP₂ . . . DP_(n) from the control element18 to a plurality of LED packages 26-1, 26-2 . . . 26-n. In certainembodiments, any number (n) of LED packages may be provided to form anLED display. As illustrated, the control element 18 is configured tosend the plurality of data packets DP₁, DP₂ . . . DP_(n) along the datastream 126 to the plurality of LED packages 26-1, 26-2 . . . 26-n. Eachof the data packets DP₁, DP₂ . . . DP_(n) may be configured, forexample, as described for the data packet 124 of FIG. 26A or 26B. Agrouping of the data packets (e.g., one or more combinations of DP₁, DP₂. . . DP_(n)) may form one of a plurality of data sets 128-1, 128-2 . .. 128-n that correspond to a particular grouping of the data packetsDP₁, DP₂ . . . DP_(n) that is received by a particular LED package 26-1,26-2 . . . 26-n. For example, the data set 128-1 corresponds to thegrouping of data packets DP₁, DP₂ . . . DP_(n) that is received by afirst LED package 26-1, the data set 128-2 corresponds to the groupingof data packets DP₂ . . . DP_(n) that is received by a second LEDpackage 26-2, and so on. In certain embodiments, a particular datapacket (e.g., a first data packet DP₁) is configured for a correspondingLED package (e.g., the first LED package 26-1). In this manner, the datapackets DP₁, DP₂ . . . DP_(n) are received by the first LED package26-1, which is configured to take an action based on a first commandcode of the first data packet DP₁, remove the first data packet DP₁ fromthe data stream 126, and pass through or retransmit the data packets DP₂. . . DP_(n) to the adjacent LED package 26-2. In a similar manner, theLED package 26-2 is configured to take action and remove the data packetDP₂ and pass through or retransmit the remaining data packets DP_(n).This sequence continues until the remaining data packet DP_(n) of thedata set 128-n is received by the remaining LED package 26-n. Forcertain display applications, each of the LED packages 26-1, 26-2 . . .26-n will retain an operating state from their corresponding data packetDP₁, DP₂ . . . DP_(n) until the control element 18 sends a new data set128-1 for the corresponding LED package 26-1, 26-2 . . . 26-n. Incertain embodiments, the control element 18 may be configured to providea portion of the data stream 126, such as a bit pattern/code or atransmission delay, that indicates to the LED package 26-1, 26-2 . . .26-n that the previous data set 128-1, 128-2 . . . 128-n is complete andto look for a next data set 128-1, 128-2 . . . 128-n. For transmissiondelays between different data sets 128-1, 128-2 . . . 128-n, a timedelay may include a range from 1 microsecond to 0.1 seconds thatprovides a sufficient timeout for the LED packages 26-1, 26-2 . . . 26-nto begin looking for the next data set 128-1, 128-2 . . . 128-n. For LEDdisplay applications, each data set 128-1, 128-2 . . . 128-n maycorrespond to a data frame or a video frame for the LED display. Forother LED applications, each data set 128-1, 128-2 . . . 128-n maycorrespond to an operating state such as a general illumination colorpoint and/or brightness level, or a static image to be collectivelyprovided by the LED packages 26-1, 26-2 . . . 26-n. In certainembodiments, the first data packet DP₁ that is configured for the firstLED package 26-1 may comprises a same data length as the second datapacket DP₂. In other embodiments, the first data packet DP₁ may comprisea data length that is larger than a data length of the second datapacket DP₂ in order to transfer more information, such as color selectdata, brightness level data, setup data, calibration data, temperaturecompensation data, and/or option select data to the first LED package26-1.

FIG. 28 is a schematic diagram illustrating a cascading flow of theplurality of data packets DP₁, DP₂ . . . DP_(n) from the control element18 to the plurality of the LED packages 26-1, 26-2 . . . 26-n and a flowof one or more talk-back data packets TB₁, TB₂ . . . TB_(n) to thecontrol element 18. The control element 18 and the data stream 126provide the data sets 128-1, 128-2 . . . 128-n with groupings of thedata packets DP₁, DP₂ . . . DP_(n) to the LED packages 26-1, 26-2 . . .26-n as described for FIG. 27 . In FIG. 28 , the first LED package 26-1is configured to receive and take an action to remove the first datapacket DP₁ from the data stream 126 and subsequently replace the firstdata packet DP₁ with a first talk-back data packet TB₁ in the data set128-2 or the data stream 126 exiting the first LED package 26-1. In asimilar manner, the remaining LED packages 26-2 . . . 26-n may beconfigured to receive corresponding data packets DP₂ . . . DP_(n) andsubsequently replace them with corresponding talk-back data packets TB₂. . . TB_(n). The talk-back data packets TB₁, TB₂ . . . TB_(n) may thenform a data set 128-c that is configured to communicate informationconcerning the LED packages 26-1, 26-2 . . . 26-n back to the controlelement 18 for monitoring. In certain embodiments, the talk-back datapackets TB₁, TB₂ . . . TB_(n) are configured to communicate one or morestates of the LED packages 26-1, 26-2 . . . 26-n, such as one or more ofoperating temperature, operating current, or other operating states suchthat the control element 18 may alter or add additional data tosubsequent data sets 128-1, 128-2 . . . 128-n based on one or more ofthe talk-back data packets TB₁, TB₂ . . . TB_(n). The talk-back datapackets TB₁, TB₂ . . . TB_(n) may also be configured to provide datachecksum parity, or other data verification to the control element 18.In such embodiments, the command codes of one or more of the datapackets DP₁, DP₂ . . . DP_(n) may include codes or signals configured todirect or prompt the active electrical element 30 of corresponding LEDpackages 26-1, 26-2 . . . 26-n to provide the talk-back data packetsTB₁, TB₂ . . . TB_(n). As such, one or more of the LED packages 26-1,26-2 . . . 26-n and the corresponding active electrical elements withineach of the LED packages 26-1, 26-2 . . . 26-n may be configured toreceive input data (e.g., one or more of the data packets DP₁, DP₂ . . .DP_(n)) and introduce additional data (e.g., one or more of thetalk-back data packets TB₁, TB₂ . . . TB_(n)) to the data stream 126.

FIG. 29 is a schematic diagram illustrating a cascading flow of theplurality of data packets DP₁, DP₂ . . . DP_(n) from the control element18 that additionally includes data packets DP_(ALL-1), DP_(ALL-2) thatare configured to provide information to all of the LED packages 26-1,26-2 . . . 26-n that receive the data stream 126. The control element 18and the data stream 126 provide the data sets 128-1, 128-2 . . . 128-nwith groupings of the data packets DP₁, DP₂ . . . DP_(n) to the LEDpackages 26-1, 26-2 . . . 26-n as described for FIG. 27 . In certainembodiments, the data sets 128-1, 128-2 . . . 128-n additionally includeone or more of the data packets DP_(ALL-1), DP_(ALL-2) that areconfigured as common or broadcast data packets for all of the LEDpackages 26-1, 26-2 . . . 26-n. In this regard, the first LED package26-1 is configured to receive and respond to the data packetsDP_(ALL-1), DP_(ALL-2) and additionally pass or retransmit the datapackets DP_(ALL-1), DP_(ALL-2) along the data stream 126 so that theremaining LED packages 26-2 . . . 26-n may also receive and respondaccordingly. In certain embodiments, one or more of the data packetsDP_(ALL-1), DP_(ALL-2) direct all of the LED packages 26-1, 26-2 . . .26-n to turn on or turn off, or provide a brightness level for all ofthe LED packages 26-1, 26-2 . . . 26-n in response to user input orambient light sensing. In other embodiments, one or more of the datapackets DP_(ALL-1), DP_(ALL-2) may be configured to direct the LEDpackages 26-1, 26-2 . . . 26-n to provide the talk-back data packetsTB₁, TB₂ . . . TB_(n) as described for FIG. 28 . In certain embodiments,the same data set 128-1, 128-2 . . . 128-n may include a first datapacket DP_(ALL-1) and a second data packet DP_(ALL-2), each of whichprovides a different common instruction to the LED packages 26-1, 26-2 .. . 26-n, such as DP_(ALL-1) instructing the LED packages 26-1, 26-2 . .. 26-n to turn on and DP_(ALL-2) providing a common brightness settingfor the LED packages 26-1, 26-2 . . . 26-n. In FIG. 29 , the datapackets DP_(ALL-1), DP_(ALL-2) are illustrated at the beginning and theend of the data sets 128-1, 128-2 . . . 128-n; however, in otherembodiments, the data packets DP_(ALL-1), DP_(ALL-2) may be arranged inany location within the data sets 128-1, 128-2 . . . 128-n. In certainembodiments, the data packets DP_(ALL-1), DP_(ALL-2) may beretransmitted through the LED package 26-n to form the data set 128-cthat is received by the control element 18.

FIG. 30 is a schematic diagram illustrating a cascading flow of theplurality of data packets DP₁, DP₂ . . . DP_(n) from the control element18 that additionally includes one or more continuation data packets CDP₂that are configured to provide additional information to at least one ofthe LED packages 26-1, 26-2 . . . 26-n. The control element 18 isconfigured to provide the data sets 128-1, 128-2 . . . 128-n thatinclude the data packets DP₁, DP₂ . . . DP_(n) to the LED packages 26-1,26-2 . . . 26-n as described for FIG. 27 . In certain embodiments, thedata sets 128-1, 128-2 . . . 128-n additionally include the continuationdata packet CDP₂ that is configured to provide additional data orinformation to at least one of the LED packages 26-1, 26-2 . . . 26-n(e.g., a second LED package 26-2 in FIG. 30 ). In this regard, thecontinuation data packet CDP₂ is arranged after the data packet DP₂ andbefore the data packet DP₃ in the data sets 128-1, 128-2 . . . 128-n ofthe data stream 126. Additionally, a command code of the continuationdata packet CDP₂ may be configured such that the first LED package 26-1passes the continuation data packet CDP₂ through and the second LEDpackage 26-2 removes and responds to the continuation data packet CDP₂after removing and responding to the data packet DP₂. In certainembodiments, the continuation data packet CDP₂ includes color selectdata and/or brightness level data that may be additional to color selectdata and/or brightness level data received from the data packet DP₂. Incertain embodiments, the continuation data packet CDP₂ includes at leastone of setup data, option select data, and calibration data. Forexample, in certain embodiments, the active electrical element 30 of oneor more of the LED packages 26-1, 26-2 . . . 26-n may be arrangedwithout flash memory and continuation data packets CDP₂ as disclosedherein may be configured to provide one or more transfer functionsfollowing a reset or an initial start-up condition. The transferfunctions may comprise temperature compensation information, gammafunctions, and the like.

According to embodiments disclosed herein, a plurality of LED packagesmay be serially arranged to receive a cascading flow of data packets.The plurality of LED packages may form an array of LED packages that mayform at least a portion of an LED display panel, an LED sign panel, or ageneral lighting panel. In such embodiments, one or more of the LEDpackages may comprise an active electrical element as previouslydescribed that receives and takes actions to one or more of the datapackets. In certain embodiments, the array of LED packages may bearranged on a panel in a serpentine arrangement that is configured toprovide the cascading flow of data packets while also providing areduced footprint of electrical routing or traces between the LEDpackages.

FIG. 31 is a partial plan view illustrating a routing configuration foran LED panel 130 that is configured for operation according toembodiments disclosed herein. In FIG. 31 , a plurality of LED packages26 are arranged in rows and columns to form an LED pixel array. Each LEDpackage 26 may include the plurality of LEDs (e.g., 28-1 to 28-3 of FIG.2 ) that form an LED pixel, the active electrical element (e.g., 30 ofFIG. 2 ), and a plurality of package bond pads 48-1 to 48-4 aspreviously described. In FIG. 31 , the package bond pads 48-1, 48-3 ofeach LED package 26 are configured as communication ports for sendingand receiving a cascading flow of data packets of a data stream. Inparticular, each package bond pad 48-3 is preassigned as an input port(indicated as “DIN” for data-in) for the data stream, and each packagebond pad 48-1 is preassigned as an output port (indicated as “DOUT” fordata-out) for the data stream. Each package bond pad 48-2 is configuredas a voltage port (VDD) and each package bond pad 48-4 is configured asa ground port (GND). In this manner, a data stream may be received atthe package bond pad 48-3 of the LED package 26 at the lower rightcorner of the LED panel 130 (designated as “Input”). At least a portionof the data stream may then exit the LED package 26 via the package bondpad 48-1 to be received by an adjacent LED package 26. A plurality ofcommunication bus lines 132-1 to 132-3 for the data stream are arrangedto connect the package bond pad 48-1 of one LED package 26 with thepackage bond pad 48-3 of the next LED package 26. In certainembodiments, the communication bus lines 132-1 to 132-3 are arranged toserially connect the LED packages 26 in a serpentine manner. In FIG. 31, the communication bus lines 132-1 to 132-3 serially connect the LEDpackages 26 from right to left across the bottom row of the LED panel130 and from left to right across the next row up from the bottom row.This sequence repeats for each additional row of the LED panel 130 toform the serpentine arrangement. Depending on the alternating directionof the serial connections from row to row, different ones of thecommunication bus lines 132-1 to 132-3 may comprise different lengths tomake connections between the package bond pads 48-1 and 48-3 of seriallyconnected LED packages 26. For example, the communication bus lines132-1 may comprise a shorter length and alternate from row to row withthe communication bus lines 132-3 that have greater lengths. Asillustrated, the communication bus lines 132-2 are arranged to connectone row to another and may comprise a same or similar length as thecommunication bus line 132-1. In this manner, all of the communicationbus lines 132-1 to 132-3 may be arranged on a same layer or plane of theLED panel 130 while providing serial connections for a data stream tothe LED packages 26. While not shown, at least some power connectionsfor the LED packages 26 may be arranged on different layers or planesthan the communication bus lines 132-1 to 132-3.

FIG. 32 is a partial plan view illustrating a routing configuration foran LED panel 134 that includes a plurality of LED packages 26 withselectively assignable or bidirectional communication ports according toembodiments disclosed herein. In FIG. 32 , the plurality of LED packages26 are arranged and connected in a serpentine manner with rows andcolumns to form an LED pixel array. Each LED package 26 may include theplurality of LEDs (e.g., 28-1 to 28-3 of FIG. 2 ) that form an LEDpixel, the active electrical element (e.g., 30 of FIG. 2 ), and theplurality of package bond pads 48-1 to 48-4 as previously described. InFIG. 32 , the package bond pads 48-2 (VDD) and the package bond pads48-4 (GND) are configured in a similar manner to FIG. 32 while thepackage bond pads 48-1 (D2), 48-3 (D1) of each LED package 26 areconfigured as communication ports for sending and receiving a cascadingflow of data packets of a data stream. As illustrated, each of thepackage bond pads 48-1 is arranged in an upper left corner of each LEDpackage 26 and each of the package bond pads 48-3 is arranged in a lowerright corner of each LED package 26 in a similar manner to FIG. 31 . InFIG. 32 , the package bond pads 48-1, 48-3 are configured as selectivelyassignable communications ports based on how the communication bus lines132-1 to 132-3 are arranged to input and output the data stream througheach of the LED packages 26. In this regard, the communication bus lines132-1 to 132-3 may be arranged to input or output the data stream fromeither of the package bond pads 48-1, 48-3 of each LED package 26. Atstart-up or after a reset of the LED panel 134, when a certain LEDpackage 26 initially receives the data stream, the active electricalelement of the LED package 26 is thereby configured to identify a firstone of first and second communication ports (e.g., one of the packagebond pads 48-1, 48-3) that receives an input signal from the datastream, selectively assign the first one of the first and secondcommunication ports as an input port, and selectively assign a secondone of the first and second communication ports (e.g., the other of thepackage bond pads 48-1, 48-3) as the output port. In this manner, thepackage bond pads 48-1, 48-3 may be configured as bidirectionalcommunication ports within each LED package 26. As such, certain LEDpackages 26 may have package bond pads 48-1 assigned as input ports,while other LED packages 26 in the same LED panel 134 may have packagebond pads 48-1 assigned as output ports. In certain embodiments, theactive electrical element of each LED package 26 may comprise circuitryconfigured to selectively assign the input and output communicationportions. For example, the active electrical element may comprisecircuitry that includes a tri-state buffer such that the activeelectrical element may assign an input port and an output port in aregister when an input communication signal is received. By providingsuch selectively assignable communication ports, the routing of thecommunication bus lines 132-1 to 132-3 between the LED packages 26 maybe simplified with reduced lengths, thereby providing lower costs andenabling higher resolution for the LED panel 134.

FIG. 33 is a partial plan view illustrating another routingconfiguration for an LED panel 136 that includes the plurality of LEDpackages 26 with selectively assignable communication ports according toembodiments disclosed herein. In FIG. 33 , the plurality of LED packages26 are arranged and connected in a serpentine manner with rows andcolumns to form an LED pixel array. Each LED package 26 may include theplurality of LEDs (e.g., 28-1 to 28-3 of FIG. 2 ) that form an LEDpixel, the active electrical element (e.g., 30 of FIG. 2 ), and theplurality of package bond pads 48-1 to 48-4 as previously described. InFIG. 33 , some of the package bond pads 48-1 to 48-4 are provided with adifferent arrangement than the illustration of FIG. 32 . In particular,the package bond pad 48-1 is configured as a ground port (GND) in FIG.33 , the package bond pad 48-2 remains a voltage port (VDD), and thepackage bond pads 48-3 (D1), 48-4 (D2) are configured as selectivelyassignable communication ports. In this manner, the selectivelyassignable communication ports are arranged closer to one another withina same LED package 26 and closer to the selectively assignablecommunication ports of an adjacent LED package 26. As such, thecommunication bus lines 132-1, 132-2 may be further simplified withreduced lengths between the LED packages 26. In particular, thecommunication bus lines 132-1 may form straight lines between adjacentLED packages 26 along each row of the LED panel 136. The longercommunication bus lines 132-2 connect one row to another and arearranged about a periphery of the LED panel 136.

FIG. 34 is a partial plan view illustrating the routing configurationfor the LED panel 136 of FIG. 33 with the addition of voltage lines 118and ground lines 122 according to embodiments disclosed herein. Byhaving the plurality of LED packages 26 with one or more selectivelyassignable communication ports (e.g., one or more of the package bondpads 48-1 to 48-4), the simplified routing arrangement of thecommunication lines 132-1, 132-2 allows a simplified routing arrangementfor the voltage lines 118 and the ground lines 122 for the LED panel136. In particular, such a routing configuration allows thecommunication lines 132-1, 132-2, the voltage lines 118, and the groundlines 122 to all be arranged on the same layer or plane of the LED panel136. In certain applications, it may be beneficial to arrange one ormore of the voltage lines 118 or the ground lines 122 on differentplanes than the communication bus lines 132-1, 132-2 to improve powerdistribution, reduce voltage sagging from trace resistance, and reducenoise from crosstalk and other sources. In certain embodiments, thecommunication bus lines 132-1, 132-2 and the voltage lines 118 may bearranged on a first layer or plane of the LED panel 136 and the groundlines 122 may be arranged on a second layer or plane of the LED panel136 with electrical vias connecting the ground lines 122 to the packagebond pads 48-1 of each LED package 26. Subset distribution on the secondlayer or plane of the LED panel 136 may be provided to reduce the numberof electrical vias.

In each of the FIGS. 31-34 , the LED packages 26 are illustrated withfour package bond pads 48-1 to 48-4. It is understood that in certainembodiments, the LED packages 26 illustrated in any of the FIGS. 31-34may comprise additional numbers of package bond pads. In certainembodiments, the LED packages 26 may have at least two additionalpackage bond pads configured to provide a clock signal in and a clocksignal out to provide synchronization or other timing sequences for theLED packages 26. In certain embodiments, serially connected LED packages26 may be configured with self-clocking configurations or configurationsfor receiving self-clocking signals, and, accordingly, the clock inputmay not be required. In certain embodiments, additional package bondpads may be configured to receive additional voltage inputs for powersavings. For example, one or more red LED chips within an LED package 26may run at lower voltages with a different voltage input than one ormore blue or green LED chips within the same LED package 26.Additionally, one or more logic circuitry arrangements in the activeelectrical element 30 may run at lower voltages with a different voltageinput.

As disclosed herein, serially connected LED packages 26 may beconfigured with temperature or other compensation, calibration,correction, or transfer function capabilities. Such capabilities ortechniques may include the use of one or more look up tables,calculations based on transfer coefficients, and combinations of look uptables with transfer coefficient calculations that provide piece-wisecontinuous transfer functions. In certain embodiments, one or more ofthe data packets DP, the continuation data packets CDP, or the common orbroadcast data packets DP_(ALL) may comprise a command code that isconfigured to prompt an active electrical element in one or more of theLED packages 26 to allow communication from such look up tables and/ortransfer coefficient calculations to a single LED package 26, asubgrouping of LED packages 26, or to all of the LED packages 26 in thedata stream 126.

As disclosed herein, LED packages are disclosed that include an activeelectrical element configured to receive data from a data stream andtake one or more actions at least partially in response to the datareceived. In certain embodiments, the active electrical element may takeone or more actions based on a command identified by the data receivedfrom the data stream in combination with one or more of a current stateof the LED package or a previous command received by the activeelectrical element.

FIG. 35 is a schematic diagram illustrating various inputs andcorresponding actions for active electrical elements according toembodiments disclosed herein. As illustrated, the active electricalelement 30 is configured to receive an input data stream 126A and actaccording to the data stream 126A and various inputs and internal states138-1 to 138-n that are used to identify one or more correspondingactions 140-1 to 140-n to take. In particular, the one or more inputsand internal states 138-1 to 138-n are received by control logic 141 ofthe active electrical element 30. The one or more inputs or internalstates 138-1 to 138-n include a current state 138-1 of the activeelectrical element 30 (and corresponding LED package 26), a currentcommand 138-2 that corresponds to a command code received from a currentportion of the input data stream 126A, a prior command 138-3 thatcorresponds to a previous command code received from a previous portionof the input data stream 126A, and one or more additional inputs ( . . .138-n). The current state 138-1 may include a reset or startup conditionfor the active electrical element 30, such as resetting registers to aninitial state. If the LED package 26 is arranged with bidirectionalcommunication ports, the initial state may include resetting thebidirectional communication ports to look for input signals. The currentstate 138-1 may also include waiting for data input from one or morecommunication ports. After receiving data from the input data stream126A, the current state 138-1 may include maintaining an operatingcondition of the LED package 26, or implementation of a common orbroadcast command and any corresponding continuation data commands. Uponreceiving the current command 138-2, the control logic 141 of the activeelectrical element 30 may then identify the one or more actions 140-1 to140-n to take based on one or more combinations of control logic 141inputs and internal states 138-1 to 138-n, and may include changing thecurrent state 138-1. The one or more actions 140-1 to 140-n may includetransmitting or retransmitting data 140-1 from the input data stream126A to an output data stream 1268, transmitting LED data 140-2 such asa talk-back packet to the output data stream 126B, or any number ofother actions 140-3, 140-4 . . . 140-n, including energizing LED chipsor other elements of the LED package 26, turning on or off an output ofthe LED package 26, sending data to calibration registers according tothe input data stream 126A received, identifying and assigningbidirectional communication ports of the LED package 26 as differentones of an input and an output port, changing data rates according tothe input or output data stream 126A/126B, implementing a specific setof options for the LED package 26, or changing a driving condition ofthe LED package 26. In this regard, the active electrical element 30 maycomprise a finite state machine that is configured to identify and takeactions based on current or previous input commands and one or morefinite or current states of the LED package 26.

FIG. 36 is a schematic diagram illustrating the active electricalelement 30 comprising a finite state machine 142 according toembodiments disclosed herein. The active electrical element 30 may beconfigured according to any number of states 144-1 to 144-4 thatcorrespond to the current state 138-1 of FIG. 35 . A startup or resetstate 144-1 may comprise an initial state for resetting registers andcommunication ports to the initial state. After the startup or resetstate 144-1, the active electrical element 30 may advance to acommunication port setup state 144-2 where the active electrical element30 waits for data input from a data stream. Upon receiving data input,the active electrical element 30 may assign an input port and an outputport for the corresponding LED package. Depending on the command codesreceived from various input signals, the active electrical element 30may advance to one of command states 144-3, 144-4. The command state144-3 corresponds to implementing and/or maintaining an operatingcondition of the individual LED package of the active electrical element30 according to a command code received. The command state 144-4corresponds to implementing and/or maintaining a common or broadcastoperating condition for all LED packages in a data stream. In normaloperation, the active electrical element 30 may advance from the startupor reset state 144-1 to the communication port setup state 144-2, beforeadvancing and cycling between the command states 144-3, 144-4 accordingto various command codes received along with other conditions such as atime out condition. As illustrated, all of the various states 144-1 to144-4 may loop back to themselves until a condition or command isprovided to change the active electrical element 30 to another of thevarious states 144-1 to 144-4. In certain embodiments, a command or acondition may change one of the various states 144-1 to 144-4 to adifferent one of the various states 144-1 to 144-4, as indicated by thedashed lines between different ones of the various states 144-1 to144-4. While only four states 144-1 to 144-4 are illustrated, the activeelectrical element 30 and the finite state machine 142 may haveadditional states according to embodiments disclosed herein. As such,FIG. 36 is provided as a high-level conceptual view of the basicoperation of the active electrical element 30. It is understood that thesame operation could be represented many different ways such ascombining the command states into one and demoting the first commandcondition to a subordinate state. In certain embodiments, all states144-1 to 144-4 may be configured with one or more timeout conditionsthat change a particular state 144-1 to 144-4 to a previous one of thestates 144-1 to 144-4 that may ultimately force a reset condition. Inthis regard, the active electrical element 30 may avoid being stuck inan unresponsive state 144-1 to 144-4.

In certain embodiments disclosed herein, LED packages include activeelectrical elements that are configured to detect adverse operatingconditions or corresponding error signals from one or more LEDs withinthe LED package. In certain embodiments, an active electrical elementmay be configured to provide and switch between both forward and reversebias states to the one or more LEDs. A forward bias state is provided toactivate or turn on the one or more LEDs, and a reverse bias state maybe separately provided to the one or more of the LEDs for othercapabilities, including current leakage measurements and reverse biasvoltage measurements. In certain embodiments, active electrical elementsmay be configured to provide forward voltage monitoring andcorresponding adjustments to drive signals for the one or more LEDs. LEDpanels are disclosed that comprise multiple LED packages configured toprovide both forward and reverse bias states. The LED panels may beconfigured such that one or more of the LED packages are capable ofrunning self-check routines at start-up or at other intervals or times.Such self-check routines may include comparing reverse leakagemeasurements with reverse leakage requirements and forward voltagemeasurements with forward voltage requirements for any of the LEDswithin each LED package. Such self-check routines may also include atemperature assessment for any of the LEDs. In certain embodiments, thereverse leakage measurements and forward voltage measurements may beadded to or may replace data that is transmitted back to a controlelement (e.g., 18 of FIG. 28 ). In response to unsuitable reverseleakage values, the active electrical element of a particular LEDpackage may shut down a particular LED within the LED package, shut downan LED pixel within the LED package, or shut down the entire LED packageduring normal operation of the LED panel in order to not draw currentaway from other LEDs, LED pixels, or LED packages. In response todeviations in forward voltage measurements, the active electricalelement of a particular LED package may responsively adjust a drivesignal, such as a PWM signal, for one or more of the LEDs within thepackage. In certain embodiments, an exemplary self-check routine maycomprise cycling through each LED to perform an initial brightnessmeasurement, performing internal reverse leakage and/or forward voltagemeasurements, and providing one or more diagnostic signals via an LEDcolor or pulse sequence for an external machine to detect and decode. Incertain embodiments, the self-check routine may provide an output signalindicating at least one of a passing or a failing condition for LEDswithin the package. The output signal may be communicated as a digitalsignal to an electrical port. In other embodiments, the output signalmay be communicated as an optical signal through one or more of the LEDswithin the package. In certain embodiments, the self-check routine mayrepeat the steps where the LEDs are electrically activated in a slowermanner in order to provide a visible signal to a human observer. In thismanner, the optical signal may comprise a code that can be interpretedfrom blinking of the one or more LEDs with predetermined colors,duration, and/or counts. In certain embodiments, the optical signal mayfirst be communicated at high speed that is undetectable or difficult todetect by a human observer, followed by communication at lower speeds toprovide human-readable code for human detection. The LED packages may beconfigured to perform such self-check routines automatically at powerstart up or the LED packages may be configured to perform suchself-check routines when directly connected to a separate power sourcefor testing. Additionally, a time delay may be provided between higherspeed communication at power-on and the lower speed communication codethat is significant enough so that a controller has time to send acommand to stop the self-check routine before the lower speedcommunication is displayed or transmitted. As such, a display screen mayonly blink according to the higher speed communication when power isfirst applied and a master controller can send an all-off command almostinstantly after power up. In this manner, initial blinking at higherspeeds during power up will be difficult to detect by a human observer.

FIGS. 37-42 are provided as general schematic and block diagramillustrations to represent concepts related to active electricalelements described herein. While FIGS. 37-42 are illustrated as generalschematic and block diagrams, various configurations and additionalsupport elements and circuitry may be present in various embodiments. InFIGS. 37-42 , any line connecting different elements may comprise asingle line or multiple lines depending on the application and type ofsignal (e.g. analog or digital) transmitted. Again, these diagrams areintended to convey concepts in a general manner. Addition of otherresistive, capacitive, and active elements may be required to achievethe desired function and performance. Other arrangements such as sourceand/or sink drivers are also considered. Additionally, otherarrangements such as using one ADC with a multiplexer switch instead ofseparate ADC inputs for each node is understood to be within the scopeof this disclosure. Also as before, separate voltage inputs can be usedfor LEDs of different voltage requirements (e.g., a separate voltageinput for red LEDs than a voltage input for green or blue LEDs).

FIG. 37 is a schematic diagram illustrating embodiments where an activeelectrical element 30 is configured to detect normal or adverseoperating conditions of at least one LED 146 according to embodimentsdisclosed herein. As illustrated, a driver 148 of the active electricalelement 30 is substantially an analog interface of the active electricalelement 30 and includes a pullup resistor R6 that is set with a highresistor value (e.g., 10,000-100,000 ohms), a threshold detector 150,and a resistor network R1-R5 of different resistor values with selectionswitches FET1-FET3 that are respectively coupled with the resistersR3-R5. The threshold detector 150 may include a comparator/operationalamplifier configuration for communicating error (ERR) signals to thecontrol logic 141. Such error signals may include an electrical short oropen state for the LED1, among others. The control logic 141 is adigital interface of the active electrical element 30 and includesresistor select (R-Select) and PWM circuitry that are coupled with thedriver 148. A cathode of the LED 146 is coupled with the pullup resistorR6, the threshold detector 150, and the resistor network R1-R5. Innormal operation, the selection switches FET1-FET3 allow selection ofthe resistors R3-R5 to provide predetermined current limits and aselection switch FET4 is coupled with the PWM circuitry of the controllogic 141 to provide brightness control for the LED 146. When the LED146 is in an electrical short state, an error is detected as a highvoltage, such as above 2 V or above 3 V, and a corresponding errorsignal is communicated to the control logic 141. When the LED 146 is inan electrical open state, an error is detected as a low voltage, such asbelow 0.5 V depending on the specific resistor selection. While only theLED 146 is illustrated, the concepts described herein are alsoapplicable to multiple LED arrangements, where separate or multiplexedthreshold detectors 150 are configured with each LED. As with previouslydescribed embodiments, the active electrical element 30 as configured inFIG. 37 may be incorporated into the same LED package as one or moreLEDs (e.g. LED 146). Additionally, the active electrical element 30 maybe configured to communicate with and respond to commands from anothercontrol element (e.g., the control element 18 of FIG. 1B).

FIG. 38 is a schematic diagram illustrating embodiments where the activeelectrical element 30 is configured to provide both forward and reversebias states to at least one LED 146 according to embodiments disclosedherein. In certain embodiments, the control logic 141 includes a reversebias control output signal that, with appropriate active elements, isconfigured to supply either near-Vss or near-Vdd voltage levels to theLED 146 in accordance with the output signal. Since the nomenclature“reverse bias” implies that a high level on the control logic 141 outputproduces a reverse bias condition, the output signal could simply becoupled with an inverter 152 that is provided in the driver 148. Assuch, the LED 146 may be either forward biased or reverse biaseddepending on a particular operating state. The inverter 152, or inverterlogic element, may have sufficient output characteristics to drive theLED 146. As with other aspects, the addition of other elements may berequired to meet all requirements. In FIG. 38 , an ADC 154 is configuredto detect a voltage at the LED 146 relating to an operating condition ofthe LED 146. As such, the ADC 154 is arranged to replace the thresholddetector 150 of FIG. 37 . In certain embodiments, the ADC 154 comprisesat least one of a resistor-capacitor (RC) circuit or analog filter thatis arranged in the driver 148 and digital filter circuitry that isarranged in the control logic 141. The ADC 154 may further comprise acomparator, a sampling element with digital feedback, and additionalfiltering in the digital domain. Other arrangements/methods for analogto digital conversion are contemplated. In order to measure an operatingcondition such as reverse leakage of the LED 146, the control logic 141may apply a reverse bias to the LED 146 such that an anode of the LED146 becomes near 0 V. In a reverse biased state with the PWM circuitryturned off, the cathode of the LED 146 coupled to the pullup resistor R6would be near V_(dd) if the LED 146 demonstrates suitably low reverseleakage. If the LED 146 is leaky under the reverse biased state, thenthe cathode of the LED 146 would have a lower voltage. This can besensed with the ADC 154 or limit sensor and used by the control logic141 to take appropriate action such as shut down the LED 146 and notifythe master control element 18 through the communication protocol. Inthis regard, the ADC 154 may form a level sensor that is configured toprovide an error signal while the LED 146 is in a reverse bias state. Assuch, the ADC 154 is configured to detect a voltage relating to anoperating condition of the LED 146 while the LED 146 is in a reversebias state.

In other embodiments, the control logic 141 may shut down one or moreLEDs within an LED package or the control logic 141 may shut down anentire LED package in response to detected reverse leakage. In stillother embodiments, the control logic 141 may adjust control signals tothe LED 146 in response to detected reverse leakage. As illustrated, thedriver 148 may include the resistor network R1-R5 and the selectionswitches FET1-FET4 and the control logic 141 may include the R-Selectcircuitry and the PWM circuitry as described for FIG. 37 . As mentionedabove, during a reverse biased state for the LED 146, the PWM circuitrywould be switched off. In certain embodiments, such configurations ofthe active electrical element 30 may allow for adjustment and improvedcontrol of operating conditions of the LED 146 beyond detecting voltageslevels and responding only to pass and fail states. The resistor networkR1-R5 serves as a current limiting circuit for the LED 146 and in thismanner, without active feedback, doesn't precisely control the currentof the LED 146 in response to small LED voltage changes. These changesare generally observed over the life of the LED 146. The forward voltagelevel feedback of the LED 146 from the ADC 154 may be used as part of acalculation to determine and/or adjust a PWM duty cycle for the LED 146.For example, if the ADC 154 detects a decrease in forward voltage levelsfor the LED 146, the control logic 141 may responsively increase the PWMduty cycle for the LED 146 to compensate for the brightness differencethat would otherwise be observed. This pseudo-current control may bepreferred over other methods of current control because of it requiresfewer resources (e.g., additional chip space and power) to implement.Along with the forward voltage level feedback of the LED 146, transfercurves, temperature compensation data, and input brightness level datamay also be part of the calculation for determining and adjusting thePWM duty cycle. Additionally, since the ADC 154 can provide voltagelevel monitoring of the LED 146 to the control logic 141, electricalshort or electrical open states for the LED 146 may also be detected. Inthis manner, the ADC 154 is configured to detect a voltage relating toan operating condition, such as forward voltage levels, of the LED 146while the LED 146 is in a forward bias state. According to embodimentsdisclosed herein, the ADC 154 may be configured to transmit measureddata (e.g., reverse leakage and forward voltage measurements) to theactive electrical element 30 for serial output to a master controlelement (e.g., the control element 18 of FIG. 1B). While only the LED146 is illustrated in FIG. 38 , the concepts described herein are alsoapplicable to multiple LED arrangements, where separate ADCs 154 areconfigured with each LED or a network of switches (e.g., a multiplexer)allows one ADC 154 to take voltage measurements from several LEDs. Aswith previously described embodiments, the active electrical element 30as configured in FIG. 38 may be incorporated into the same LED packageas one or more LEDs (e.g., LED 146).

FIG. 39 is a schematic diagram illustrating embodiments where theresistor network R1-R5 and the corresponding selection switchesFET1-FET3 of FIG. 38 are replaced with a current source 156 in theactive electrical element 30 according to embodiments disclosed herein.In FIG. 39 , the pullup resistor R6 and the inverter 152 are coupledwith the LED 146 as described for FIG. 38 . The current source 156 isconfigured to provide current to the LED 146 that is selectable (e.g., afew levels) or adjustable (e.g., many levels). Since the schematicrepresentation for the current source 156 is more general than theresistor network R1-R5 and the corresponding selection switchesFET1-FET3 of FIG. 38 , subsequent diagrams will use the current source156 to represent any method for controlling LED current, including theresistor network R1-R5 and the corresponding selection switchesFET1-FET3 of FIG. 38 . The control logic 141 includes current-selectcircuitry (or resistor-select circuity for FIG. 37 ) that is generallyused to set a maximum current or brightness level based on chip size orthe like for the LED 146. Such selection may generally be made atinitial setup and may not necessarily be changed afterward. In certainembodiments, the PWM may be omitted and the LED 146 may be run by thecurrent source 156 alone as previously described with the Howlandcurrent pump of FIG. 11E. In certain embodiments, the current source 156is equipped with built-in feedback and accordingly, feedback from theADC 154 may not be needed. In certain embodiments, temperaturemeasurement feedback may be provided to the current source 156 by one ormore components of the ADC154. While only the LED 146 is illustrated inFIG. 39 , the concepts described herein are also applicable to multipleLED arrangements. As with previously described embodiments, the activeelectrical element 30 as configured in FIG. 39 may be incorporated intothe same LED package as one or more LEDs (e.g., LED 146).

FIG. 40 is a schematic diagram illustrating multiple LED embodimentssimilar to schematic diagram of FIG. 39 . As illustrated, a separate oneof pullup resistors R6-1 to R6-3 in the active electrical element 30 iscoupled to corresponding ones of multiple LEDs 146-1 to 146-3.Additionally, each of the LEDs 146-1 to 146-3 is coupled with acorresponding ADC 154-1 to 154-3 and a corresponding current source156-1 to 156-3. In FIG. 40 , the inverter 152 is configured to change orswitch from forward bias states to reverse bias states for each of theLEDs 146-1 to 146-3. In other embodiments, the active electrical element30 may comprise a separate inverter 152 for each of the LEDs 146-1 to146-3. As discussed earlier, separate V_(dd) voltage inputs could beutilized to save power by driving the LEDs 146-1 to 146-3 at theirrespective voltage levels with less power dissipation within the activeelectrical element 30. While the current sources 156-1 to 156-3 areillustrated, a resistor network (e.g., R1-R5 of FIG. 38 ) and selectionswitches (e.g., FET1-FET3 of FIG. 38 ) may also be configured for eachof the LEDs 146-1 to 146-3. As such, the active electrical element 30 ofFIG. 40 is configured to provide electrical open detection, electricalshort detection, forward voltage monitoring, and reverse leakagemonitoring for each of the LEDs 146-1 to 146-3 and responsively adjustor shut off individual ones or groups of the LEDs 146-1 to 146-3. Aswith previously described embodiments, the active electrical element 30as configured in FIG. 40 may be incorporated into the same LED packageas the LEDs 146-1 to 146-3. While a plurality of the ADCs 154-1 to 154-3is illustrated, a single ADC may be provided to detect voltages orvoltage levels at multiple nodes such that the single ADC is configuredto provide at least one of reverse leakage measurements and forwardvoltage measurements for a plurality of the LEDs 146-1 to 146-3.

FIG. 41 is a schematic diagram illustrating the active electricalelement 30 of FIG. 40 configured with multiple ports that include asupply voltage V_(dd), ground V_(ss), and bidirectional communicationports (input/output (I/O) Port 1 and I/O Port 2) according toembodiments disclosed herein. In FIG. 41 , in addition to the four portsof V_(dd), V_(ss), I/O Port 1, and I/O Port 2 on the left side of theschematic, the active electrical element 30 includes four ports on theright side of schematic that are coupled with the LEDs 146-1 to 146-3.As illustrated, the LEDs 146-1 to 146-3 are electrically coupled withthe inverter 152, the pullup resistors R6-1 to R6-3, the ADCs 154-1 to154-3, and the current sources 156-1 to 156-3 as previously described.In other embodiments, the current sources 156-1 to 156-3 may be replacedwith corresponding resistor networks and selection switches aspreviously described. The bidirectional communication ports I/O Port 1and I/O Port 2 are electrically coupled with one or more I/O buffers158. The I/O buffers 158 include circuitry (e.g., various buffers andtri-state buffers) that along with the control logic 141 are configuredto assign the bidirectional communication ports I/O Port 1 and I/O Port2 as either input (Data In) or output (Data Out) communication portsbased on how the active electrical element 30 is connected within thesystem. In response to an input data connection at either of thebidirectional communication ports I/O Port 1 and I/O Port 2, the controllogic 141 will accordingly assign an input port direction and an outputport direction. The control logic 141 may include one or more additionalelements that are generally illustrated in FIG. 41 , such as a memoryelement, a clock or oscillator, and/or a filter and ADC that areconnected to a temperature sensor and a resistor-capacitor for providingthermal management capabilities. In certain embodiments, one or more ofthe ADCs 154-1 to 154-3, or a separate ADC, may be configured to providetemperature measurements by measuring a voltage provided by atemperature sensor.

FIG. 42 is a schematic diagram illustrating the active electricalelement 30 of FIG. 41 configured with polarity-agnostic orpolarity-independent input capabilities according to embodimentsdisclosed herein. As illustrated, a switching network 160, such as anactive switching network, may be arranged that receives or connects withmultiple connections (e.g., ports P1-P4) from input ports or pins andconfigures separate signal lines as one of the V_(dd), V_(ss), Data in,and Data out signal lines. As such, the ports P1-P4 form a plurality ofpolarity-agnostic connection ports that are arranged to receive ortransmit various signals. In certain embodiments, the switching network160 includes circuitry configured to self-configure irrespective of whatorder the ports P1-P4 are connected. Exemplary circuitry for theswitching network 160 may include a network of actively controlledswitches, such as MOSFETS with gates that are biased according tovoltage levels sensed on the inputs. In certain embodiments, theswitching network 160 may provide part of the function for the I/Obuffers 158 of FIG. 41 . As such, it may be desirable to combine thefunctions of the I/O buffers 158 of FIG. 41 into the switching network160 in certain embodiments. As illustrated by the dashed lines withinthe active switching network 160 of FIG. 42 , each individual one of theports P1-P4 are capable of being connected as any single one of theV_(dd), V_(ss), Data in, and Data out signal lines. In this manner, theactive electrical element 30 of an LED package may comprise theswitching network 160 and one or more bidirectional communication portssuch that package bond pads (e.g., 48-1 to 48-4 of FIG. 21 ) of the LEDpackage form polarity-agnostic connection ports that may be connected toany one of V_(dd), V_(ss), input communication, and outputcommunication. For output communication, at least one of the multipleports (e.g., ports P1-P4) may accordingly be configured as an outputcommunication port. Since the switching network 160 includes power aswell, power pins must be designated first and switched to theappropriate nodes. This power input can be accomplished through passivecircuitry (e.g., an RC network controlling gates of FETs). By way ofexample, FIG. 43 is a general schematic diagram illustrating afour-input rectifier 162 that may be used to provide initial power tothe switching network 160 of FIG. 42 . As illustrated, each of the portsP1-P4 are coupled with a pair of low voltage components such as bipolardiodes, Schottky diodes, and the like. Such diodes may consume too muchpower because of their voltage drop (particularly for low-voltage LEDcomponents), and accordingly, the four-input rectifier 162 may only beused to initially power the switching network 160 of FIG. 42 , afterwhich active elements and logic can be used to make the final switchconnections. In this manner, the power switching network of FIG. 42 maythen use low voltage switches such as MOSFETS to provide low-resistancerouting of power pins, bypassing the diode rectifier (e.g., 162 of FIG.43 ). In certain embodiments, the MOSFETS may be included in an activerectifier of the switching network 160 that is used in combination withthe four-input rectifier 162. In other embodiments, the active rectifiermay be used in place of the 4-input rectifier 162 by replacing each ofthe diodes illustrated in FIG. 43 with actively controlled switches,such as transistors including MOSFETs and/or bipolar junctiontransistors.

As previously described, an active electrical element of an LED packageis disclosed that is configured to receive a digital code, such as acompressed digital code or encoded signal, from a control element of anLED display. For example, the active electrical element may beconfigured to receive an encoded digital signal (e.g., FIG. 20 ) thatutilizes reduced data bits in a data stream for communicating largeramounts of command codes. In this regard, the active electrical elementmay be configured to receive a compressed digital code and subsequentlydecompress the digital code for the data stream received by the activeelectrical element. As such, decompression of the digital code receivedmay include any nonlinear function or algorithm for expansion of thedata stream received, including an exponential inverse power functionthat may increase a dynamic range of the data stream. The dynamic rangeof a digital signal may refer to a range (e.g., upper and lower values)of signal levels generally described by the number of bits. One form ofcompression relates simply to how such bits are used. Bits are oftenused to generate a current or power input to an LED in a linear manner.This can be an inefficient use of the bit depth (e.g., dynamic range)for a display system because the human observer recognizes light in anonlinear fashion more akin to a logarithmic or power law function suchas used for gamma correction. The dynamic range of a given number ofbits may be small (e.g., the highest level of an 8-bit code is 255 timesthat of the lowest level, excluding zero), but that dynamic range can beextended by orders of magnitude when transforming the data to match thenonlinear response of the eye. As an example, instead of having adynamic range of 255 for 8 bits, by applying a gamma of 2.2, we get adynamic range of almost 200,000 while still only using 8 bits. With nocompression, 18 bits would be required to achieve the same level ofdynamic range. In this manner, the dynamic range may refer to a usefulnumber of bits, sampling, or resolution of the data stream for theactive electrical element. As such, active electrical elements asdisclosed herein may be configured to receive compressed data anddecompress such data to provide a greater observed and useful dynamicrange. As just described, certain embodiments, the compression anddecompression schemes may follow a power law expression (e.g., gammacorrection) to increase a dynamic range between a digital image and aperceived image by a human observer. In other embodiments, thecompression and decompression schemes may include grouping of adjacentLED pixels/packages or LED pixels/packages in close proximity to oneanother. Such grouping of LED pixels may be applicable for embodimentswhere the groups of LED pixels are under the control of a commonelectrical element in an LED display matrix. In particular, an LEDpackage may include two or more adjacent LED pixels and the compresseddata code and subsequently decompressed data code reduces datainefficiencies by eliminating redundancy within the data that may beexpected between neighboring ones of two or more adjacent LED pixels. Assuch, a common code is decoded or decompressed to provide codes for twoor more adjacent LED pixels or subpixels.

As described above for FIGS. 41 and 42 , LED packages are disclosed thatare capable of receiving compressed digital data at any of severalbidirectional communication ports or at any of polarity-agnostic packagebond pads (e.g. 48-1 to 48-4 of FIG. 21 ) and decompressing such digitaldata. Additionally, LED packages are disclosed that are capable ofreceiving a transfer function or transfer function values to be appliedwithin an LED package to any of several bidirectional communicationports or at any of polarity-agnostic package bond pads (e.g. 48-1 to48-4 of FIG. 21 ). The transfer function may comprise one or moresubsets of transfer function coefficients for the active electricalelement to interpolate. In this manner, the transfer function may becalculated in the digital domain. In certain embodiments, the transferfunction may comprise a piecewise transfer function. According toembodiments disclosed herein, the transfer function may be applied todirect or control one or more of a temperature measurement of one ormore LEDs within the LED package, or a brightness output of one or moreLEDs within the LED package, to an ADC input (e.g., the ADC 154 of FIG.38 ), to a PWM output (e.g., the PWM circuitry of FIG. 38 ), and to aDAC-controlled output of an active electrical element. As used herein, a“transfer function” refers to any type of function that may beimplemented in any number of ways to transform input data into outputdata such that the output data is different from the input data. Incertain embodiments, a transfer function may be configured to transformdata according to a linear function such as addition, multiplication,and the like. In certain embodiments, a transfer function may beconfigured to transform data according to a nonlinear function such asexponential, logarithmic, transcendental, algorithmic functions, Fouriertransforms (e.g., discrete Fourier transforms), and the like. Transferfunctions may be applied to temperature control by transformingtemperature sensor values to generate corresponding control signals forthe LEDs for temperature, brightness, or voltage adjustments, andcombinations thereof. In certain embodiments, a transfer function may beconfigured to receive and transform multiple inputs of data values frommultiple sources, such inputs from a control element (18 of FIG. 1B),inputs from a temperature sensor, and inputs that include forwardvoltage measurements or reverse leakage measurements of LEDs. Inputsfrom a control element that is external to an LED package may beconfigured as serial communication or serial input that includes desiredbrightness, calibration, and transfer coefficients, among others. Inputsfrom a temperature sensor, or inputs that include forward voltage and/orreverse leakage measurements may be internally generated within aparticular LED package. In this manner, an LED package is disclosedherein that includes an active electrical element configured to receivedata values and transform the data values according to a transferfunction. In certain embodiments, the data values comprise a compresseddata code that is received by the active electrical element, and theactive electrical element is configured to transform the compressed datacode to decompressed data code. The decompressed data code may comprisea brightness level or other control signal for an LED within the LEDpackage.

In certain embodiments as disclosed herein, active electrical elementsof LED packages are configured to receive data from a data stream thatincludes user-selectable color depth data. Color depth may refer to anumber of data bits used to indicate or represent a color of an LED oran LED pixel. For example, 1-bit color depth may include monochromaticcolors such as black and white, and 24-bit color depth may include8-bits for each of a red LED, a blue LED, and a green LED within aparticular LED package. Depending on the application, theuser-selectable color depth data may comprise color depths in a rangefrom 1-bit color depth to 100-bit color depth. In certain embodiments, auser may select a color depth for one or more LED packages within an LEDdisplay that is selectable from any one of 24-bit, 30-bit, 36-bit, and48-bit color depths. In certain embodiments, a particular bit depth(e.g., one of 24-bit, 30-bit, 36-bit, and 48-bit color depths) may beachieved by selecting a next-higher bit depth and zero-padding a numberof least significant bits relating to the difference. Depending on thecolor depth selected, the data stream received by the active electricalelement of a particular LED package may be adjusted according to a bitsize that corresponds to the selected color depth. For example, whenchanging from a larger color depth to a smaller color depth, the numberof corresponding bits and transmission time is reduced. In this manner,a bit size of the selectable color depth data is adjustable. Atdifferent communication speeds for the data stream, there can be atrade-off between bit size or depth related to color depth, frame rate,and a number of pixels or subpixels in a control chain.

As disclosed herein, active electrical elements of LED packages may beconfigured to receive various data signals, including compressed orencoded signals and color depth data that correspond to any number ofcommand codes. As previously described, the command codes may beincluded as part of data packets of a data stream. In certainembodiments, a command code for a particular LED or LED pixel mayinclude an identifier signal that indicates to the active electricalelement how the particular LED or LED pixel should respond to thecommand code. By way of example, the identifier signal may include: a“0” digital signal that indicates the command code is a single-pixelcommand code that is intended for a single LED or single LED pixel; or a“1” digital signal that indicates the command code is an all-pixelcommand code that is intended for all LEDs or all LED pixels. In certainembodiments, the single-pixel data are removed from the data stream bythe particular pixel receiving the data and may be replaced withtalk-back data or talk-back data packets as previously described.Single-pixel command codes may include any one of a skip pixel, a setbrightness return on voltage, a set brightness return temperature andstatus, and a return or talk-back reverse leakage command, among others.Skip pixel command codes allow the ability to address a particular LEDor LED pixel in a chain without affecting other LEDs or LED pixels thatare upstream. All-pixel command codes may include any one of a setbrightness for all LEDs or LED pixels, or an end of frame command code.In certain embodiments, an end of frame command code is provided toindicate that the LED or LED pixel should respond to a next single-pixelcommand code. In certain embodiments, single-pixel command codes may betransmitted or retransmitted along the chain for addressing particularLEDs or LED pixels. In this regard, the active electrical element of anLED package that responds to a single-pixel command code mayresponsively transmit the single-pixel command code with an altered codeto indicate an “executed” command code and then wait until the end offrame command code is received before responding to the nextsingle-pixel command code. Such an active electrical element may bereferred to as a pseudo-repeater in cascade communication as it receivesand retransmits data, but sometimes alters or replaces the data and doesnot always return the same data as the data received.

Examples of command codes that can be either a single-pixel command codeor an all-pixel command code (e.g., either 0 or 1 for the “All” commandbit) may include any one of a reset, a set options, a set RGBcalibration, a set RGB transfer coefficients, and a set RGB thermalcoefficients command code. In certain embodiments, the set optionscommand code may be followed with additional bytes of data where eachbit represents one of the following options: red LED off, green LED off,blue LED off, disable thermal shutdown, disable red LED shutdown,disable green LED shutdown, disable blue LED shutdown, communicationspeed 0, communication speed 1, color depth 0, color depth 1, turnoff/on parity fail, PWM type 0, PWM type 1, resistor select 0, resistorselect 1, resistor select 2, do not turn off shorted LED, use thermalcompensation, setup acknowledge to acknowledge that a power on resetcondition has been addressed, and to use voltage compensation that setsa mode where forward voltage feedback is used to adjust the PWM dutycycle. The communication speed 0 and 1 options may provide at least fourcommunication speeds for output or may be provided to detect acommunication speed from input. In this regard, an LED package isdisclosed that includes an active electrical element configured tochange or adapt a communication speed of data without a transmittedclock signal. The color depth 0 and 1 options may be configured togglebetween color depths that include 24-bit-depth, 30-bit-depth,36-bit-depth, and 48-bit-depth.

In certain embodiments, any of the foregoing aspects, and/or variousseparate aspects and features as described herein, may be combined foradditional advantage. Any of the various features and elements asdisclosed herein may be combined with one or more other disclosedfeatures and elements unless indicated to the contrary herein.

Those skilled in the art will recognize improvements and modificationsto the preferred embodiments of the present disclosure. All suchimprovements and modifications are considered within the scope of theconcepts disclosed herein and the claims that follow.

What is claimed is:
 1. A light emitting diode (LED) package, comprising:a submount; at least one LED mounted on the submount; an activeelectrical element electrically connected to the at least one LED, theactive electrical element configured to drive the at least one LED in aforward bias state and switch the at least one LED to a reverse biasstate where the at least one LED is reverse biased, wherein the activeelectrical element comprises at least two bidirectional communicationports; an input/output buffer electrically coupled to the at least twobidirectional communication ports; an inverter logic element directlycoupled to the at least one LED; and an encapsulant on the submount,wherein the encapsulant covers at least a portion of the at least oneLED and at least a portion of the active electrical element.
 2. The LEDpackage of claim 1, wherein the active electrical element furthercomprises a level sensor that is configured to provide an error signalwhile the at least one LED is in the reverse bias state.
 3. The LEDpackage of claim 1, wherein the active electrical element furthercomprises an analog-to-digital converter that is configured to providereverse leakage measurements while the at least one LED is in thereverse bias state.
 4. The LED package of claim 3, wherein theanalog-to-digital converter comprises at least one of an analog filtercircuit and digital filter circuitry.
 5. The LED package of claim 3,wherein the analog-to-digital converter is configured to detect avoltage relating to an operating condition of the at least one LED whilethe at least one LED is in the reverse bias state.
 6. The LED package ofclaim 3, wherein the analog-to-digital converter is configured to detecta voltage relating to an operating condition of the at least one LEDwhile the at least one LED is in the forward bias state.
 7. The LEDpackage of claim 6, wherein the active electrical element is configuredto adjust a drive signal of the at least one LED based on the voltagedetected while the at least one LED is in the forward bias state.
 8. TheLED package of claim 7, wherein the drive signal comprises a pulse widthmodulation signal and the active electrical element is configured toadjust a pulse width modulation duty cycle of the at least one LED. 9.The LED package of claim 1, wherein the active electrical elementcomprises a resistor network that provides predetermined current limitsto the at least one LED.
 10. The LED package of claim 1, wherein theactive electrical element comprises a current source that provides anadjustable current to the at least one LED.
 11. The LED package of claim1, wherein the inverter logic element is configured to provide thereverse bias state.
 12. The LED package of claim 1, wherein the activeelectrical element is configured to communicate with and respond tocommands from another control element.
 13. The LED package of claim 1,wherein the active electrical element is configured to receive datavalues and transform the data values according to a transfer function.14. The LED package of claim 1, wherein the active electrical element isconfigured to receive selectable color depth data.
 15. The LED packageof claim 1, wherein the at least two bidirectional communication portscomprise a first bidirectional communication port and a secondbidirectional communication port, wherein the active electrical elementis configured to selectively assign either the first bidirectionalcommunication port or the second bidirectional communication port as aninput port in response to an input signal received by the activeelectrical element, and selectively assign the other of the firstbidirectional communication port or the second bidirectionalcommunication port as an output port.
 16. The LED package of claim 1,wherein the submount is a light-transmissive submount that comprises afirst face and a second face that is opposite the first face, whereinthe at least one LED and the active electrical element are mounted onthe first face and the second face is a primary emission face of the LEDpackage.
 17. A light emitting diode (LED) package, comprising: asubmount; at least one LED mounted on the submount; an active electricalelement electrically connected to the at least one LED, the activeelectrical element configured to drive the at least one LED in a forwardbias state and switch the at least one LED to a reverse bias state wherethe at least one LED is reverse biased, the active electrical elementcomprising at least one analog-to-digital converter, the activeelectrical element further comprising at least two bidirectionalcommunication ports; an input/output buffer electrically coupled to theat least two bidirectional communication ports; an inverter logicelement directly coupled to the at least one LED; and an encapsulant onthe submount, wherein the encapsulant covers at least a portion of theat least one LED and at least a portion of the active electricalelement; wherein the at least one analog-to-digital converter isconfigured to detect a voltage relating to reverse leakage measurementsof the at least one LED while the at least one LED is reverse biased.18. The LED package of claim 17, wherein the at least oneanalog-to-digital converter is configured to detect a voltage relatingto forward voltage measurements of the at least one LED.
 19. The LEDpackage of claim 17, wherein the at least one analog-to-digitalconverter is configured to detect an electrical short condition of theat least one LED.
 20. The LED package of claim 17, wherein the at leastone analog-to-digital converter is configured to detect an electricalopen condition of the at least one LED.
 21. The LED package of claim 17,wherein the active electrical element is configured to adjust a pulsewidth modulation duty cycle of the at least one LED based on voltagelevels that are detected by the at least one analog-to-digitalconverter.
 22. The LED package of claim 17, wherein the at least oneanalog-to-digital converter is configured to transmit measured data fromthe at least one LED to the active electrical element for serial output.23. The LED package of claim 17, wherein the at least oneanalog-to-digital converter is configured to provide at least one ofreverse leakage measurements and forward voltage measurements for aplurality of LEDs.
 24. The LED package of claim 17, wherein the at leastone analog-to-digital converter is configured to provide temperaturemeasurements by measuring a voltage provided by a thermal sensor. 25.The LED package of claim 17, wherein the active electrical element isconfigured to receive data values and transform the data valuesaccording to a transfer function.
 26. The LED package of claim 17,wherein the active electrical element is configured to receiveselectable color depth data.
 27. The LED package of claim 17, whereinthe at least two bidirectional communication ports comprise a firstbidirectional communication port and a second bidirectionalcommunication port, wherein the active electrical element is configuredto selectively assign either the first bidirectional communication portor the second bidirectional communication port as an input port inresponse to an input signal received by the active electrical element,and selectively assign the other of the first bidirectionalcommunication port or the second bidirectional communication port as anoutput port.
 28. The LED package of claim 17, wherein the submount is alight-transmissive submount that comprises a first face and a secondface that is opposite the first face, wherein the at least one LED andthe active electrical element are mounted on the first face and thesecond face is a primary emission face of the LED package.
 29. The LEDpackage of claim 1, wherein the active electrical element comprisespulse width modulation (PWM) circuitry configured to control abrightness of the at least one LED and the PWM circuitry is turned offwhen the at least one LED is reverse biased.
 30. The LED package ofclaim 17, wherein the active electrical element comprises pulse widthmodulation (PWM) circuitry configured to control a brightness of the atleast one LED and the PWM circuitry is turned off when the at least oneLED is reverse biased.